Skuballer

Comes from the word "skubala" meaning trash or shit. A skuballer is someone who thinks they're really good at a sport, and gets super cocky and obnoxious, but in reality he sucks at the fore mentioned sport.

Jim: Man, Paul hogged the ball all game.
John: I know! He didn't score once. He's a huge skuballer.

Limp Dicked

To put little effort into or to barely get by on something.

John: Man, I really don't want to study for this exam next week.
Billy: Dude, you don't really need to. I completely limp dicked it and still pulled out a B.