In bocca al lupo
Literally: Into the mouth of the wolf
What it really means
Good luck! (and you reply «Crepi il lupo» — "may the wolf die")
When nonna would say it
Said before any test, exam, audition, interview, or daunting task — the Italian equivalent of "break a leg."
Picture this
Your granddaughter is about to sit her driving test. Nonna kisses both cheeks and says «In bocca al lupo!» — and woe betide you if you reply «grazie» instead of «crepi».