A couple weeks ago I went to pick my girlfriend up from dance class. I drove right past the studio, down the road another mile to her apartment and waited. She finally called me and asked where I was, and I told her outside. And only then did I realize my mistake.... So I had to call her back and tell her I was at her apartment, and I'd be there in a minute. By then she had left the studio, the door had locked, and she was stuck out in the rain. Oops.
I get it a lot when I'm grocery shopping. I'll go in for something specific like cat litter, and leave with $100 worth of groceries but no cat litter. I also do it when I'm driving, to the point that some days, regardless of where I'm going, I keep winding up back at home in between. I'll go over to the mall, then instead of going half a mile west to get to the cell phone store, I'll drive home, realize that's not where I was going, and drive 3 miles back to the cell phone store. Makes you feel stupid, really... Or if I want to turn on my computer to check one specific thing, like movie showtimes, I'll turn it on, load up my e-mail, check anandtech real quick, then turn it off. Whoops, turn it back on, totally forgot what I was doing... And everyone in the room looks at you like you're retarded.