Big-Gulp Anyone?

Driving in our car we stopped at 7-11. Michael got us both Big-Gulps. He put his in the back cup holder and I put mine in the front cup holder. About 2 minutes later he took a drink from my Big-Gulp in the front cup holder.

Me: That ones mine.
Him: Oh, well lets trade spots then because its easier for me to grab the front one while I'm driving.
(We place Big-Gulps into their new designated cup holders)
Me: Its okay, we exchange bodily functions all the time.
Him: Fluids.
Me: Oh (turning bright red in the face) that's what I meant, fluids.
Him: I would hope that we wouldn't exchange bodily functions ever!

About a minute later I grab for his drink thinking that its mine in the front cup holder. Its a vicious cycle I tell you!