Naked Melee Armageddon
Naked Melee Armageddon is one of the most aptly named online games ever created. Your simple goal is to overwhelm alien attackers by placing naked humans on the screen as fast as you can. Why everyone's naked, no one really knows, but you don't have time to sit and ponder. After just a few seconds the aliens will attack, at which point all you can do is kick back and watch the armageddon.
You have roughly five seconds before the melee begins to load the screen with as many people as you can. When an alien and a human meet, they get into a little skirmish. There are several crazy ways in which they destroy each other, such as axes, explosions, ninja moves, electrocution, etc. No matter the outcome, both the winner and loser vanish. The only way to win is by outnumbering the enemy.
Yes, it's a laughably simple game, but yes, it's fun. There are five levels of difficulty, each requiring more people to defeat the onslaught. Win or lose, nothing happens, you just go back to the title screen. Kind of like those "I Saved The World And All I Got Was This Lousy T-Shirt" things.
But you know, Naked Melee Armageddon is just too wacky to pass up. Play.
(P.S. Yeah, everyone's naked, but there's no detail and it's all a cartoon, so it's safe.)