h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Well ... it's fongool, and it's not very nice. I tried to find the exact meaning for you, and I've come up with this: according to Kevin Beary's Florentine Locutions (1991), it's properly spelled vaffanculo, a contraction of va a fare in culo, and literally means "go do [it] in the a$$," i.e., bugger off, f**k off, f**k you. "Some Italians affirm that the a$$ referred to is that of one's interlocutor, while others assert that the orifice in question is not yours or mine or anyone's in particular, but rather the universal anus," Beary says.

There ya go. Depending on the age of the students in question, you might want to change that word ... something else must rhyme with cool and drool.