Jimmy Wisniewski (voiced by John DiMaggio) is the antagonist of Steve's subplot in the Season 3 episode Amber Alert. He is a childhood bully of Steve. He picked on Steve until 7th grade when Steve's mom started having sex with him to stop doing so, and she did this every Wednesday at 2:30 P.M. for 20 years. However, when Steve told his mom to stop helping out his life, his mom cut off Wisniewski and so he challenged Steve to a fight.
Steve then miserably attempts Street Fighter attacks (Hadouken, Sonic Boom, Yoga Flame) on Wisniewski, which only gets him bloody punches to the face. Seeing how badly Steve's getting beaten up, Malloy "helps" Steve out by feeding him Power Pellets (just kidding, it's dog poop).
After Steve fails to defeat Wisniewski in combat, he (proudly) called his mom to go back to having sex with Wisniewski.