Once again, !lr is built into the Hosties Mod, though there are standalones, they all have the same settings. The major issue being that all rebels are turned red, this makes it more annoying to try for that quick knife kill, because if you miss the quick kill, there is no way you can get away as the game will have turned your player model bright red.
The other main issue with !lr, is that we do not require lr's be given, it is at the CT's discretion, for example, if I am playing CT and I have 1 t obeying orders while his entire team is rebelling just so he can have an lr, I generally deny him one because he was just being a pussy waiting for his special treatment.