If you really don't like someone you can shout out an imprecation at them. More than simply the use of bad language (although that can be involved, too), an imprecation is a damning curse wishing them nothing but ill.
Originally from a Latin word meaning to "invoke evil" or "bring down bad spirits upon." Not to be confused with implication, a similar-sounding word with the completely unrelated meaning of implying something indirectly. These are two very commonly confused words, so be careful. You don't want an imprecation blasted down upon you from someone who really cares about language.