The given translation I see is "buona fortuna" :o
In bocca al lupo is a common idiom, I guess originating from hunters: the answer is "crepi", so the whole ritual is like "May you chance upon the wolf" "May he die"... It's similar in usage to how you'd say "Break a leg" in English.
Thanks for the additional explanation! I also found it in a dictionary but after losing a heart for choosing only "buona fortuna". That's why I said it's unfair. How could I have possibly guessed it can also be that wolf sentence? :P
Buona fortuna is definitely accepted now. But I've been told that the actual sentence is seen as bad luck in Italian (to wish someone good luck). Italian's are very crazy with their rituals and superstitions - I think it's wonderful!
But yeah, sucks if you lost a heart for it. But on the bright side, getting it wrong teaches you something new about Italian culture :) - What if somebody now gets "Buona fortuna" right and moves on without ever learning about the history like you got to!