The inability for people (in my experience, women) to interact with another human being for more than 5 minutes without checking their cel phones. I'm 35, and I'm single, and this is one of my biggest pet peeves about other humans. If I sat there on a first date and watched the Brewers game, well, that wouldn't go over well.... but somehow it's becoming socially acceptable for people to interact with their phones instead of the people around them.