Idioms rarely translate word for word, but the pictures they paint stick. Six that Italians use before exams, interviews and journeys:

Idiom	Literally	Meaning
In bocca al lupo!	into the wolf's mouth!	good luck!
Crepi!	may it die!	the reply: thanks!
toccare ferro	to touch iron	to touch wood
essere nato con la camicia	to be born wearing a shirt	to be born lucky
portare sfortuna	to bring bad luck	to jinx (something)
Acqua in bocca!	water in the mouth!	don't breathe a word!

In bocca al lupo is the standard good-luck wish — and the answer is always Crepi! (may the wolf die!) or Crepi il lupo! Some Italians consider grazie in reply bad luck.