It might have been mentioned but:

The "Can't I make a reflex save?" guy
This guy wants to make a reflex save for almost anything that should involve armor class. Shot at by an Arrow? "can't I make a reflex save?" Bonus points if they've been playing for years and still ask this.

I had a player that insisted that critical hits could be negated with reflex saves.

The "one skill is as good as the other" guy
This guy wants to use his Craft: Alchemy to make a dress, or craft: Armor Smith to make a boat. Alternatively if he failed a Knowledge Arcana roll to remember important traits of some magical beast, he'll want to try again with Knowledge Religion, and then Knowledge Dungeoneering. No, Magical Beasts is Arcana, any info the other knowledges would give you is fringe at best.

The player inspiring this one played a cleric of some God of Secrets and forbidden knowledge. And he insisted that because of his god he could make Knowledge Religion rolls for everything under the sun.