This exchange between Jorah and Dany in A Game of Thrones:
Dany: Viserys says he could sweep the Seven Kingdoms with ten thousand Dothraki screamers.
Jorah:*snort* Viserys couldn't sweep a stable with ten thousand brooms.
As the story of how Arya disarmed Joffrey is being told by both sides in the Court, Renly Baratheon is ordered by the king to be escorted out because he's started laughing at Joff. He says that he is perfectly capable of finding the door himself and continues to laugh at Joff's sword name as he was leaving.
Renly (to Joff): Penchance later you'll tell me how a nine-year-old girl the size of a wet rat managed to disarm you with a broom handle and throw your sword in the river.
Tyrion defending himself against Catelyn's accusations on the way to the Vale leads to this exchange:
Also the fact that while he's mad that she's accusing him falsely of the attempted murder of a child, he is equally mad that she thinks he's dumb enough to bet against Jaime in a tournament.
At one point, Eddard Stark thinks about Gregor Clegane, including the fact that dogs are afraid to enter his hall. By this point Summer, Grey Wind, and Shaggydog have kicked out all the dogs from Winterfell's hall.
Ned Stark's inner thoughts about how uncomfortable the Iron Throne is and how much he hates doing Robert's job.
"Damn Aegon for his conceit and damn Robert and his hunting."
Sansa's proclamation that she wants to marry Joffrey.
A bit of dark humor comes when Dany, after learning that the wine seller who tried to poison her was offered a lordship for assassinating the remaining Targaryens, remarks that Drogo must have earned one for killing Viserys.
Pyp congratulating Jon Snow on being given Longclaw: