The syringe, or are modkills more outright like "as the group was walking down the street, a guy with a flag that said "MOD" fell out of the sky and shot leafy 35 times, ending him" or is it more descreet?
A modkill is when you are breaking the rules, or just being silly. If I decide that you are taking away from the storyline, I take away the problem: you.