Has its moments, but not reccomended.
Whacked`s single player is simple: you take a contestant on a game show and play through 4 levels to get the grand prize, which is actually a ride to Hell. Sure I just ruined the story for you, but trust me, if you bought this game just recently, you'll be finding out the story in about a half-hour.
The games characters are plain bizzare, ranging from a bunny with his hand and feet cut off to a chick who's only clothing is 2 censorship bars over her privates. These characters have a large diversiy of things they say and think, although gameplay wise, they all play exactly alike.
At least the levels are diverse. Levels in Whacked go from Space to Hell itself. These maps have tons of weapons that can be funny at times but will mostly get on your nerves. Also, on some levels you will die in an unexpected was that will leave you thinking "What the F**k?"
Whacked! has an Xbox Live installed on it, but really, are you gonna drop Halo 2 for this? The one place Whacked! really shines is humor, but don't expect to get it from actuall gameplay. You will find it mostly in the comercials that play as you progress through the game. My personal favorite is the Public Service Announcement on things you shouldn't do, like try to melt a cop car windsheild.
But that aside, Whacked! won't leave you laughing. Well, it might, but that laughter will be at the games shallow and boring gameplay.