a. A person that is so involved in drugs, alcohol, sex, and general debauchery above what is conceiveably possible.
b. A shady character.
c. Someone that appears to have no moral judgment, self-respect, or general hygiene to the point where he/she is a total laughingstock that must be avoided.
a.) The noun form of sketchy.
b.) Someone who participates in activities that you wouldn't want the majority of people to know about because people will think you're creepy, and avoid you.
Normal behavior of a sketchball include:
Hitting on girls outside of preppy suburban bars.
Sitting by themselves at night on their sidekick/blackberry
"Accidently" sleeping with people
Lurking people like crazy on facebook/myspace/AIM.
Man, Wesley is such a sketchball, he was lurking that girls myspace at the show, while SHE was at the show, somehow he ended up "accidently" sleeping with her, after he hit on her friend last night.