How to prevent teamkilling?

I am bored of teamkilling so I asked the question. K?

You need to edit the source. In a script, there's a line or two where it damages/kills a the player it comes in contact with. Add a line somewhat like this to prevent damage being taken if the other person is on the same team.

if not p.TeamColor == a.TeamColor then
	--damage
end

Of course, you'll need to edit the variables.