The word spastic is used differently depending on location which has led to some controversy and misunderstanding. The term generally originates from spasticity, a medical condition characterized by hypertonia, or a high degree of muscle tightness. Spasticity underlies spastic diplegia and many other forms of cerebral palsy.
The term can also be used in a pejorative context, as in spazz. Their level of severity depends on whether one understands them as they are used in the United States or the United Kingdom . In the UK they are not used in polite society and are considered highly abusive terms that generally denote people deemed to be mentally or behaviorally deficient. In the US they are more closely associated with hyperactivity or clumsiness and carry little offensive connotations.
The word was historically a medical term for a sufferer of spasticity. It is generally regarded as having been brought to public knowledge and popularized from its use in the name of The Spastics Society (now SCOPE), a charity for people with cerebral palsy, which was founded in 1951 and has a reasonably high public profile from its street collections and charity shops.
However, the term began to be used as an insult, and became a term of abuse for an ungainly or physically inept person, derived from a common misconception that those with any physical disability resulting in spasticity would necessarily also have a mental or developmental disability. It is often colloquially abbreviated to forms such as "spa", "spaz", "spazzer", "spack", "spacko" and "spacker".
Evolution of the term in the United Kingdom
During the International Year of Disabled Persons (1981) the BBC attempted to bring the hidden world of physical disabilities to a widespread audience by presenting Paul Reeds, Fir House, County Dublin, brave struggle with a debilitating condition. Several episodes of the children's show Blue Peter featured a cerebral palsy sufferer (described as a "spastic") named Joey Deacon. Rather than encouraging understanding, the show generated unexpected negative consequences as Mr Deacon became the subject of ridicule from many of the show's viewers. Phrases such as "You Joey" and "You spaz" became popular insults amongst children at that time. When the Spastics Society changed its name to SCOPE in 1994, it was a widely held belief is that this was due to Blue Peter's legacy.
It is therefore argued that Blue Peter caused "spastic" and its abbreviations to develop highly offensive connotations. In reality, these words had been used in a derogatory manner for some years previously. However, their usage did significantly increase as a result of the broadcasts, particularly amongst children. The widespread casual use of these terms as playground insults by children who did not fully understand physical disability caused great distress to sufferers and their carers and contributed to an increased stereotyping and misunderstanding of disability throughout society.
It is probably an exaggeration to say that the Blue Peter shows were the sole contributor to the charity's name change, but they were undoubtedly a substantial factor. The rebranding can also be seen as part of the anti-discrimination movement of that period, and resulted in the terms dropping out of common usage as the majority of British society came to regard them as offensive and politically incorrect. The new name has led to the occasional pejorative use of related expressions such as Scoper or Scopey.
In the mid-1980s, some people attempted to "reclaim" the term. This is the meaning in the Ian Dury and the Blockheads song Spasticus Autisticus, and it is also used in the Ben Elton book Gridlock. There is also a movie called "I'm Spasticus" (a wordplay on "I'm Spartacus"). The group 2NU best known for their early 90s Top 40 song "Ponderous" wrote a song called "Spaz Attack".
The current connotations of the word are well-illustated by a BBC survey in 2003, which found that "spastic" was the second most offensive term in England relating to disability (retard was deemed most offensive) . In 2007, Lynne Murphy, a linguist at the University of Sussex, described the term as being "one of the most taboo insults to a British ear".
Evolution of the term in the United States
On occasion North American TV series or movies, such as Buffy the Vampire Slayer, Firefly and Meatballs, will use the term "spaz" and get a different reaction from British and American audiences. In American slang, the term "spaz" is inoffensive, most Americans consider it casual slang for clumsiness, sometimes associated from overexcitement, excessive energy, or hyperactivity. Its usage has been documented as far back as the mid 1950s. In 1965, film critic Pauline Kael, explained to her readers, "The term that American teen-agers now use as the opposite of 'tough' is 'spaz'. A spaz is a person who is courteous to teachers, plans for a career..and believes in official values. A spaz is something like what adults still call a square." New York Time columnist similarly explained to readers that spaz meant "You're strictly from 23-skidoo." Benjamin Zimmer, an Editor for the "American Dictionary" and researcher at the University of Pennsylvania's Institute for Research in Cognitive Sciences, writes that by the mid 1960s the American usage of the term spaz shifted from "its original sense of 'spastic or physically uncoordinated person' to something more like 'nerdy, weird or uncool person.'" By contrast, in a June 2005 newsletter for "American Dialect Society", Zimmer reports that the "earliest [written] occurrence of uncoordinated "spaz" (as opposed to uncool "spaz")?" is found in Elastik Band's 1965 "undeniably tasteless garage-rock single" "Spazz".
Later in 1978, Steve Martin on Saturday Night Live, in a skit with Bill Murray called "Nerds" introduced a character Charles Knerlman, aka "Chaz the Spaz." Bill Murray later starred in the movie Meatballs which had a character named "Spaz." Both shows portrayed a spaz as a nerd or somebody uncool in a comic setting. Thus, while Blue Peter shaped the modern British understanding of the term, American viewers were being bombarded with a different image. In time, the term spaz, like its counterparts nerd and geek, lost its offensive nature and evolved into terms often used in self-deprecation.
The difference in understanding of the term, between British and American audiences, was highlighted by an incident with the golfer Tiger Woods; after losing the US Masters Tournament in 2006, he said, "I was so in control from tee to green, the best I've played for years... But as soon as I got on the green I was a spaz." His remarks were broadcast and drew no attention in America. But they were widely reported in England, where they caused offence and were condemned by a representative of SCOPE and Tanni Grey-Thompson, a prominent paralympian. On learning of the furor over his comments, Woods' representative promptly apologized.
Most Americans were surprised when they learned about the controversy. In fact, at least one American dictionary (Merriam Webster's) makes no reference to cerebral palsy in its definition or word origins. It simply defines "spaz" as a shortening of the word "spastic" and "one who is inept".
Many products in America use the word Spaz as part of their name because of the American connotation of energy and excitement.
Controversy arises if products are sold in the UK or other parts of Europe under the same name. In particular the manufacturers and importers of the Spazz wheelchair were criticised by the British SCOPE charity when they put the wheelchair on sale in the UK. SCOPE expressed a fear that the usage of the word as an insult would increase again, after a steady decline since the 1980s.
A caffeinated lipbalm created by a police officer is called "SpazzStick."  "Spaz-Stix" is the company that produces high end remote control car/plane paints.
An energy drink is called "Spaz Juice" and has a slogan, "all the energy you need to annoy everybody else."
On June 29, 2007, Ubisoft of France pulled one of their games called Mind Quiz: Your Brain Coach, for referring to players who did not perform well at the game as "Super Spastic" which can be construed in the UK as being offensive. The company stated "As soon as we were made aware of the issue we stopped distribution of the product and are now working with retailers to pull the game off the market."  Similarly, Nintendo recalled Mario Party 8 in the UK after releasing a version containing the line "[t]urn the train spastic" in its dialogue. 
- Murphy, M Lynne (2007-02-28). spastic, learning disability (HTML). Separated by a Common Language. Retrieved on 2007-08-17.
- BBC News - The s-word (2006-04-13). Retrieved on 2007-07-23.
- BBC (2003). Worst Word Vote (HTML). Ouch. Retrieved on 2007-08-17.
- Zimmer, Benjamin (2007-02-05). A brief history of "spaz" (HTML). Language Log. University of Penn. Retrieved on 2007-10-31.
- Zimmer, Benjamin (2006-04-13). Parents will never be cool (HTML). Language Log. University of Penn. Retrieved on 2007-10-31.
- Zimmer, Benjamin (2005-06-23). spaz(z), n. (HTML). Newsletter. American Dialect Society. Retrieved on 2007-10-31.
- SI.com - Golf - Agent: Tiger sorry for 'spaz' remark - Thursday April 13, 2006 4:02PM. Retrieved on 2007-06-07.
- BBC (2006-04-12). Tanni criticises "stupid" Tiger (HTML). BBC Sport. Retrieved on 2007-08-17.
- The Daily Record - NEWS - DISABLED OUTRAGE OVER WHEELCHAIR CALLED THE SPAZZ - DISABLED OUTRAGE OVER WHEELCHAIR CALLED THE SPAZZ. Retrieved on 2007-06-07.
- SPAZZSTICK dot com :: The World's ONLY Caffeinated Lip Balm!. Retrieved on 2007-06-07.
- Happy Bunny Spaz Juice - The BevNET.com Review. Retrieved on 2007-06-07.
- Brain game pulled over 'offence'. Retrieved on 2007-06-29.
- Mario's Party ended for saying "spastic". Retrieved on 2007-07-16.