I have this nasty habit of saying stupid things.
It's a shocker, isn't it?
One of the most common is when I reply with "you too" to someone helping me in a store or some other customer service situation. It just comes flying out of my mouth, even if it is completely inappropriate. It's as if I have a very specific form of Tourette's.
You can guarantee that if someone says any of the following, I will inevitably follow with an enthusiastic "you too!"
"Enjoy your movie."
"Good luck with your interview."
"Enjoy your purchase."
I also have the uncanny ability to say "you're welcome" before anyone has a chance to say "thank you."
It's a gift.