C’est pas mon rayon!
say pah maw ray-YAW!
It’s not my department!
What you say when someone asks you a question you don’t know the answer to: C’est pas mon rayon!
Un rayon means a counter–the kind that demarcates the various departments in a large store. You know, the glass-topped display cases, the salespeople with their carefully-protected keys, the cash register with the cash drawer dinging open.
Of course, you could politely say I’m sorry, I don’t know, but if you’re feeling a bit smart-alecky and offhanded, C’est pas mon rayon will do the job nicely.
Note that half of the negative is missing: There’s no ne, only the pas. That’s because this is a very slangy expression. It’s not vulgar, nor it is rude language, but it’s probably bad manners. All the more fun to know know how to say it!
If you would really rather be polite, you can say, Désolé, je ne sais pas. (day-zoh-LAY, zhun say PAH.) I’m sorry, I don’t know.