Here is a bind that makes you crouch until you press the button again

bind mouse2 crouch
alias crouch "bind mouse2 -crouch;+movedown;echo AutoCrouch On"
alias -crouch "bind mouse2 crouch;-movedown;echo AutoCrouch Off"

And of course you should be able to tell here is a Mute Alias.

bind F9 mute
alias mute mute_on
alias mute_on "alias mute mute_off;s_volume 0;echo Mute ON"
alias mute_off "alias mute mute_on;s_volume 0.6;echo Mute OFF"
