AutoInsult is a fun little program that generates insults for you in a variety of styles. It then copies them into the clipboard (as text) so that you can paste them into emails, documents, or wherever else a good insult might be needed. You can also get it to pop-up an insult at regular intervals.

Whilst AutoInsult is certainly not Politically Correct, it is not obscene or vulgar.
The user can also specify the degree of offensiveness.