You too

I once heard a comedian, I believe it was Brian Regan, do a stand up routine about how funny it is when we mindlessly use the phrase "you too" as a response to people every day. Sometimes it makes no sense, and yet out of habit we continue to use the phrase.

For instance, you tell the postman "have a good a good day" and he responds "you too." That's good usage.

Now consider: the waitress tells you to "enjoy your meal," and without thinking you reply "you too." What meal is she eating?
Or the guy in the toll booth tells you to "have a great stay in Florida" and you ignorantly reply "you too." He lives here!
Or the appliance man at Home Depot tells you "good luck with your new dishwasher" and you say "you too." Doubtful that he also has a recently purchased dishwasher.

Or the girl today in the pizza store. I was waiting in line for my lunch, observing the other customers and people watching (as I am want to do on occasion). The man in front of me, obviously in his late 40's, was currently flirting with the cute young cashier. He was telling her about his life in the corporate world, sadly attempting to flirt with the girl by simultaneously flaunting his acheivements while adoring her youth. She was eating it up.

As he walked out the front door, he looked over his shoulder and cast one longing look at the co-ed and teased, "have fun in college."

She flirted back. "You too."