The best definition of the word "meh" that I've come across is comparing it as a "verbal shrug" - The word has plenty of usage on the Interweb (see: Words that the Internet Gave Us), usually to put someone or something down as weak or boring.
The apathetic expression has certainly wormed its way to the English vocabulary. In 2008, HarperCollins announced that the word would be included in the Collins English Dictionary as "an expression of indifference or boredom, or an adjective meaning mediocre or boring."
My question to you, Neatoramanauts, is simple: Is there an equivalent of "meh" in your language? How would you say "meh" in your language?