One who is weird, does not conform to the norm, or is stalkerish. A sketchball can also be someone that does completely random things..such as eat french fries with mustard. Sketchballs are usually males.

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.

a weird person

someone extremely sketchy

This activity occurs when you are in public and you see a police officer. The game goes as followed.
1. Spot a police officer or someone in law enforcement.
2. Look at him/her and make sure he/she sees you clearly.
3. Run as fast as you can in the opposite direction.
4. Results may vary.

Someone who in the presence of other people makes them feel uncomfortable or weirded out. In some cases such acts will result in the "non-sketchball" to physically or verbally abuse the sketchball"

A person who suffers from the long-term effects of sleep deprivation, and/or drug-induced psychosis. Usually one who is addicted to Methamphetamine.