Here's my favorite. Students that Show up, quit for three months, show up three times a session, and basically take a year to reach Green Belt.
There's this one student that was a High Green when I was a white belt. I'm now a Green belt lol. This guy does his forms like he's drunk (too fast, too sloppy). And he never ever kicks above his own belt level. Even in sparring.
Then there's another student who is a fellow Green Belt. He can kick well, but sometimes his kata looks subpar. The really annoying thing about him is he thinks he outranks me because he's been a green belt before. So he tries to make me move out the senior belt position in my row.
Then there's the worst of them... This one kid was an Orange Belt when I was a White Belt. Now we are both Green Belts, and he too thinks he outranks me. Even though I got my green belt three weeks before him. The guy not only sucks at forms, but he doesn't even remember Dan Gun, or Half of Do San.
One of these days I'm taking my old Blue/Red belt certificates to class to shut these kids up.