Every multi-tasker is guilty of this one. Your visits to the bathroom are often an excuse to email or tweet when you know your date would find it rude if you did so at the dinner table. A unisex restroom likely means that twice the number of people are waiting in line behind you. Save that tweet as a draft and wait to watch the latest Harlem Shake video until after you've done your downtown shake. Multi-tasking is wonderful, just not in this particular environment.
10. Don't Make the Stall Your Office