So, i just watched it for the second time last night, and I started trying to find all the little jokes The Joker made during the course of the movie. Some of them were twisted, so that only he would find them funny, but they were still jokes or gags. Here's the ones I thought were hilarious, but I'd love to see if anyone found any others.
*extreme spoiler warning*
Being one of the masked bank robbers to hear what the other guys thought.
Telling the other bank robber the bank manager was out of ammo.
"Nooo, I kill the bus driver."
Getting away from a bank robbery in a school bus.
Stealing a little of the mob's money as part of the plan to steal it all.
Custom made clothing - jacket and vest made from card table felt, shirt print is of the back of standard poker cards
Taunting the mob bosses with "Like the suit? You should, you bought it."
The 'you'll poke your eye out' magic trick.
"I'm not crazy. I'm not crazy" (Crazy people can't tell if they're crazy)
"Now let's not blow this out of proportion." (as he shows the grenades in his jacket)
Having Gamble's men 'try out' for a 'position' in the gang.
"Good evening, Ladies and Gentlemen. We are tonight's entertainment."
Eating the hors d'ouvres loudly and tossing the champagne out of the glass before 'drinking' from it.
"Where's Harvey Dent?" (Spoken in a 'gentlemenly' accent in room full of rich people)
Grooming himself when approaching Rachel.
"Poor choice of words!"
Killing the commissioner and then replacing his honor guard.
Planting the joker card in the Judge's file, then when she ignores it, he fills her car with joker cards that go flying all over when the car explodes.
Obstructing the path of the police escort for Harvey Dent with a burning fire truck. (I can almost hear him saying "It's a fire truck! Get it!? HAHAHA"
Attacking the convoy from a circus truck.
The circus truck says "Laughter is the best medicine." but that wasn't ironic enough for the Joker, so he spray painted an "S" in front of "Laughter".
"I like this job."
Clapping for Gordon's promotion.
Lying about who was at which address, and having both Batman and Harvey listen as Rachel died.
"I want my phone call."
*silently mouths*"Six?"
Wearing a Harvey Dent campaign sticker while in Harvey's hospital room.
"I'm just like a dog chasing cars; I wouldn't know what to do with it if I caught one."
Convincing Harvey Dent, a man who stands for justice and fairness, that there is no plan, only anarchy.
"I'm only burning my half [of the pile of money]. You can do whatever you want with your half."
Switching the hostages with the thugs.
"This is where the irresistable force meets the immovable object" (A logical impossibility; if the force is irresistable, then...)
*End spoilers*
I'm sure there are more, those are just the ones i could remember.