Plowing through a whole bunch of Zombies while in a car can be this, especially the Infected ones, who like charging towards you.
Not just that. How about tackling through a whole bunch of zombies with Sam B?
Sometimes, just sometimes, a Walker will goof up and walk face-first into a wall. They just bounce off and correct their path, but good lord is it funny.
This also sometimes happens with the Infected. It's even funnier because they run screaming into the wall.
The screams Thugs make when they're electrocuted or set on fire. Its high-pitched, whacked-in-the-bollocks noises really doesn't go with their large size, but that just makes it even more humorous, especially when they're shocked and they spazz around like nobody's business.
Once, This Troper tossed a molotov at a Thug. While he burned to death in the usual manner, when he fell over, his head exploded on impact. Equally funny is the time when I hit a Walker so hard he flew backwards and his legs popped off.
An instance this troper experienced, mixed with Crowning Moment Of Awesome. Once, on a street in the city, took on a number of Infected and a Thug, and heard the approach of a Suicider but wasn't exactly sure of it's location. After my weapon broke, I was overwhelmed and killed. When I respawned, I found that the respawn point was only a few feet away. The horde charged at me, when I heard the unmistakable "HELP ME" of the Suicider, very close by. I turned and saw it right behind me, so I quickly dodged left, the Suicider exploded and wiped out the whole horde. Nice Job Fixing It Exploding Zombie.
This troper continues to go into hysterics whenever he uses the "Pick-And-Ohm" mod on pretty much any zombie in sight. It is basically an electrified pickaxe that, when getting a critical hit, knocks Walkers, Infected, and even Thugs at LEAST ten feet backward, opening them up for a jump-stomp. Definitely handy against Thugs.
If you let a Ram gear up to charge you and then jump out of the way, the Ram will run right past you. It's more amusing to do this while standing in front of something, as the Ram will slam right into whatever was behind you.
Okay, you're geared up to play the game after seeing that trailer. You play through the first two or three minutes at the hotel and end up in a shack a lifeguard is defending. You help him and it turns out to be Steve Blum, playing a big Samoan, who throws a knife at a zombie and cheerily says, "Thanks mate." Given the tone of the game best Mood-Swinger moment ever.
One of Xian's one liners is sending the infected to hell. Look at Banoi. Look at how bad it is. She's kind of late on that score.
Critical hits can be this. Especially with Sam B's preference of the knockdown blunt weapons - it is just so unintentionally hilarious when you baseball bat a Thug or Floater so hard they not only fly off to who knows how far but that hit also rips BOTH their legs off that just.. Flop down there where it stood.