When you cause someone's head to explode by any method.
Ganondorf's side special in Super Smash Bros. Brawl Getting a head shot with a high caliber sniper rifle or shot gun.
When a chestburster Alien gets lost and pops out someones head.
Sticking c-4 to someone's forehead with Snake in Super Smash Bros. Brawl.
Headsplosion is the best way to finish people off in stamina mode
I got an awesome headsplosion with my 50-cal
Ewww, that little alien just splattered his brain with a headsplosion