* Wearing baseball caps at the dinner table
* Not letting people get a word in edgewise
* Smokers waving their smoke in everyone's faces
* Nonhandicapped people parking in the handicapped spots
* People who won't pull over for funeral processions or even ambulances!
(It happens! The ambulance people then have to maneuver around them... grrr... good luck with that karma, buddy!)
ETA: I don't mind if people type in 1337 or say "w00t!", but it bothers me when they write "u" for "you", "2" for "two", and "4" for "for".... etc....