Yeah, there is one in almost every group. The player who likes to fight the plot, get the party in all sorts of messes that could have easily been avoided, and actually turn party members against one another. If there is one thing a GM needs in order to run a successful campaign, is flexibility. That and the patience of a saint.
In the group that I was in (in which this comic is loosely based upon), we did actually pass notes instead of just stating our actions if we needed them to be secret, or a surprise. If the group ever split up, many times the GM would require actions be sent in by notes. This is because we commonly considered player knowledge the same as character knowledge. There are several times the GM (including myself if I was running the campaign at the time) would call players out on it, but we tried to get away with it every chance we got. Hence the GM requiring notes when we were split up.
The reason behind this can be illustrated by the party almost wiping itself out in a dungeon once when we were split up. We eventually traversed the dungeon (both groups) and actually came to adjoining rooms with a door in between. There was a thief in group A along with a high level wizard and fighter, group B consisted of another high level wizard, fighter, ranger and cleric. The thief heard noises in the next room, silently alerted his fellows and they hatched the plan to open the door and the wizard would cast fireball on the center of the room inside. The door was locked, so the thief starts to pick it (after looking for traps, of course). The GM alerts group B that the handle on the door on the opposite side of the room is rattling. The wizard in group B informs the GM that once the door opens, he will send a fireball in through the door into the other room. All of this was done through notes, which we had been doing more or less since we split up, so we weren’t aware that the other half of the party was on the other side, nor were we suspicious becuase the GM suddenly started making us send notes.
Needless to say, once the door was open, chaos ensued. Two fireballs from fairly high level wizards come careening past each other and explode in opposite rooms. Most of us didn’t make our savings throws, so we took full damage, and that toasted many of us (we weren’t in top condition after battling some of the monsters in that dungeon). It was the cleric making his that saved a lot of us from rolling up a new character. He healed what he could with the spells and potions he had left. One of the wizards outright died, and we had to carry him back to get ressurected. Fun times.