I was a kiddo when I last saw this, but it was a ranchy high school comedy (like late 2000s early 2010s?). The two protagonist were teenagers (unpopular) the main one was a skinny nerd robot. I think it was on adult swim possibly? The other character was fat comedic relief. I believe the series had only a few episodes. I apologise for not enough details, it's been a very long time.
Robotomy seems like a pretty good match.
Thrasher and Blastus are two teenage robots who live on the planet of Insanus. Their planet is inhabited by murderous robots who seek to kill one another for no apparent reason. Slightly less horrific than their peers, the duo seeks to make it through high school, and navigate their lives with mixed results. Thrasher (Patton Oswalt), a tall and lanky robot, wishes to gain the affections of an attractive female robot named Maimy (Jessie Cantrell). Meanwhile, Blastus (John Gemberling), a short and rotund robot, just wants to be popular. As with Blastus, unlike most robots on Insanus, he is mostly sensitive and non-criminal, much to the disapproval of his mother. In his quest to be cool, however, he is incredibly impulsive and overconfident in his abilities. Thrasher, though calm and reserved, often falls prey to Blastus' badly-thought out plans.
Found with a search for
"adult swim" "high school" robots