I remember when I played Left 4 Dead, a couple of months ago, that some players were able to let their controlled character do a scaring long scream.
How did they do? Is it possible to do this also in Left 4 Dead 2?
Valve removed the vocalization commands to stop people spamming in multiplayer games, all that is left are the speech wheel that come up when you press z or x (using default controls).
Edit: This is the very hacky way of doing it through the radial commands which may or may not work.
Type in the following:
bind b "vocalize playerdeath"
b is the key you are binding to, change this to whatever you want.
Happy screaming, just don't spam the hell out of it.
Here's a step by step guide of how to do it (including a video of it in action):
Based on the steps involved, it looks like it would work in L4D2 as well.
If you're using the pc version, you can press the Z or X keys, which will open a selection wheel to select various actions for your character to perform, including laughing and screaming.
From what I know, there is no 'speech wheel' like in L4D1unless you hack. also I found there is a penelty for speaking too much (calling out names/zombies or guns). The penelty is 3-5 seconds of no speech. The cross hairs go out on a melee weapon while the penelty is in effect.