I always feel stupid when a waiter or someone says "Enjoy your meal" And I respond, "You too!"
Also, My friend and I were hanging out one night, and we were discussing if I was going to call her the next morning. I said "I'll call you at quarter to eight, okay?" And she said, "I don't know... That sounds a little early. How about 7:45?"
I facepalmed, but we laugh about it now.