Meaning of expression "avant que tu ne sortes tes meilleurs vannes"

Question

Qu'est-ce que veut dire l'expression: "Et avant que tu ne sortes tes meilleures vannes, sache que j'en bave vraiment" !

Accepted Answer

Hi Jordi, 
There is a lot of slang in this sentence, I am glad it is a C1 exercise -
balancer/ sortir des vannes = to throw/ come out with  wisecracks/digs/cutting remarks
en baver = to have a hard time of it / to suffer
( can mean to drool but not here.)
So -
Before you come out with your best wisecracks, be aware that I am really suffering!
Hope this helps!

Answer

Et avant que tu ne sortes tes meilleures vannes, sache que j'en bave vraiment. -- And before you pull your best punches, I just want you to know that I'm really drooling.sortir les meilleures vannes -- (literally:) to bring out the best valvesen baver -- to drool