Let's share our pet peeves

This Bingo card shows two dozen "pet peeves" somebody came up with, but what exactly is a pet peeve?  It's something that someone finds especially annoying.  For example, a friend said, "One of my biggest pet peeves is poor customer service."  Another friend said hers is people who use "it's" when they should write "its."  (Do you know when to use each of these?)  And lots of folks on our neighborhood listserv would say their pet peeve is people who don't pick up after their dogs.  Please share one or two of your pet peeves in the comments.