After my lunch break, on my short drive back to work, my friend called me to ask a question. As I got out of my car, I didn't feel my phone in my pocket, so I thought "Oh, shoot, I forgot my phone at home. I'll have to email my dad and see if he can drop it by."
It took me a good two minutes to realize that I had my phone... because I was talking on it.
Sadly that's not the first time I've done that.