Well, since I do RP in Bonfire a lot, I have a few peeves.
Uno, RP Fighing. I especially do not like RP fighting when you A. have a powerplayer, or B. When someone claims they know how to fight properly when they can't.
Dos, Double-Characters. This mainly happens in a TLK RP, and there's two sides of this peeve. Part one, when everyone is just minding their own business, someone randomly yells out, "OMG 2 SIMBAS!!!11!" The other side is when someone starts to argue about who's the "Real" or "Better" character.
Tres, Those-People-Who-Sit-On-The-Side-And-Critique. I'm sometimes one of those people, so shame on me. But, whenever someone isn't doing anything, and they start nagging how you're not 100% top notch, that really gets on my nerves.
That's pretty much my pet peeves...
-Sandfury