Here's stuff I constantly hear:
1. People who insist on repeating everything in each of their transmissions twice. WTF, who taught them this? I mean in class G we're supposed to realize that all the other flyers out there might not be %100 on the ball, but this is going overboard.
2. People who insist on telling me what frequency they're on. Ok, I sort of figured that out since I'M LISTENING ON THAT FREQUENCY TOO. Maybe Ok for communicating with FSS, but a little redundant everywhere else.
3. Trucker talk - you people know who you are. You know, the "over and outs", the "roger, rogers" and what not. STOP IT!
Taht's not to mention all the single case stuff I hear coming out of people's mouths. After I had instructed one student on how to respond to ATC, when they actually had to the response was an "Okie Dokie!" I just about jumped out of the airplane. Another decided that instead of "Mike" for M that "Michael" sounded more official...

Now I realize that we all flub up occasionally on the radio - it happens to the best of us - but Jebus, think before you talk out there!