Killjoy

Killjoy is a medal awarded in Halo 3 Multiplayer To obtain this medal you must kill somebody who is on a Killing Spree. You can also kill someone who is achieving a streak greater than this, such as a killing frenzy, etc. in order to earn this medal. It is represented by an octagon with a crossed-out smiley. This medal is very random as you don't know which players are on killing sprees.