The anti-MetaGamer aka 'Well my character wouldn't know that...'
This is the guy who comes to the conclusion that since the Sorcerer held his action and put his Fireball down *after* the warriors had charged out of the area of effect, that everyone else is Metagaming, and then promptly does the most incredibly stupid and self-defeating thing he can think of, like attempting to Grapple the Half-Fire Elemental Vampiric Mind Flayer.
When other players look at him in bewilderment as he's level-drained / brain-sucked / set on fire, he gets haughty and points out that '*I* don't use OOC knowledge, *my character* wouldn't know about level-drain / brain-sucking / elemental fire auras.'
Bonus coupons for the jerk who manages to get other party members killed in the process, or even arrange a TPK through said act of petulance. "Well, *obviously,* my character wouldn't know that the evil Efreeti would try to twist the wording of the Wish. Don't yell at me for playing my character right..."
Unless your character sheet says skill "Steve Erwin, Marlon Perkins or Jim Fowler: 25 or higher"
Thunderfoot gets bonus points for knowing who Jim Fowler is.
The Multitasker: this player can't just sit and listen while the other players take their combat actions or roleplay. She has to be doing something else. Unfortunately she then doesn't notice when it's her turn again. (raises hand guiltily)
Oh man, I have *list* of stuff that has to be done before my players can be trusted to sit down. No laptops. Ever. What a freaking nightmare. Never trust a group of three IT professionals who say, 'but a spreadsheet will make the game so much *faster!*' Cause it NEVER does...
Cellphones away. Computers in the room turned off, no stopping 'just to see who that was' when the IM 'ping' sounds and then spending the next 10 minutes IMing someone. Television off. No exceptions. One of the players can't leave the room and pass a room with a television on, even if it's the five year old watching freaking *Dora the Explorer,* he stops hypnotized and has to be pulled away, protesting 'I wasn't watching it!' and getting all huffy that I'm dragging him away.
It's like being a kindergarten teacher riding herd to a special needs class sometimes...
I used to fear that it was me being a boring GM, but I'm usually a *player* in this group, and I still have to go wrangle the stragglers.