The pleasant rushing sensation that accompanies epicly powning your enemies.
an 11 kill streak (within a limited time frame) in halo 3 is a killgasm. the feeling that accompanies the p0wnage is the Powngasm. Also occurs in real-life sporting events such as a hole in one in golf or a behind the back goal in lacrosse.
When you are cheated out of something by circumstances outside of your control, such as when you are stabbed in Call of Duty, or sniped in Halo, merely because the internet you are connected to lagged and left you exposed and unable to defend yourself.
"Oh sh*t my internet is giving out!"
"Yeah and you got lagknifed from behind too..."
"I would have gotten him too if my internet hadn't died!"