vaffanculo!

When I said this to Alex, he simply corrected my pronunciation.

I learned the useful word from a New Yorker profile of Beppe Grillo, a political comedian in Italy with a much-read blog. Grillo has been sponsoring V-Day protests against the convicted criminals in the Italian Parliament: Victory, Vendetta, and Vaffanculo.

Travis asked "When would it be appropriate to use 'vaffanculo'"?

Alex thundered, NEVER, it's never appropriate, that's the whole point!