Boards
People who sing along to the radio in the office.
I'm not sure which type is worse:
1) The people who just brazenly sing out loud like they're auditioning for a gig on some sort of terrible cruise ship, or;
2) The people who don't actually sing, but just quietly whine along to the small sections of the song they know.
I've got a 2) behind me right now. It's driving me crazy.