Positively Negative

From Wiki

Positively Negative is a webcomic that Entar started in late 2005. The comic consists mostly of two characters: Kevin and Robert. Kevin is an aspiring (and perspiring) inventor who has way too much time on his hands. Robert works at a fast food restaurant and has a similar surplus of expendable time. They're both a little nutty.

http://entar.quakedev.com/comics
Positively Negative Guest Art