Killing after the game isn't a big deal, I do it sometimes. I know there are some that think  "yeah, I'm hard I got that kill", but whatever.  Usually I shoot my gun in the air for a win or punch a rock for a loss.   
  
 
  
Agreed, "oh I'm so funny, I want my balls in some dudes mouth, this is original and funny" (dude, keep your fetishes out of halo, save them for your off time) 
  
- assassinate 
  
-> Karma