This show is about an "average" high school in america. It's animated, well sort of. They use real photography as background and set pieces, so there's an immediate feeling that the creators are lazier than average. Most animation studios send work to Korea or Japan when they take the lazy route, this show demonstrates a new depth of laziness.
Considering the most long running series on television doesn't actually go out of their way to enhance quality, let's move on to other critical points.
Catch phrases are a huge part of this show, they actually assign them to characters with gaudy text intros, trying to leap the writing hurtle of actually taking the time to humorously earn those catch phrases by placing them well in the first few episodes. The laziness of this show easily extends into the humour. There are more scrotum and ass jokes in the first 10 minutes than in South Park's first season. They also don't know how to tell a story or build real humour, using short cheap jokes that aren't actually funny (they represent stereotypes constantly, expecting us to get a laugh and failing miserably), and their humour building plots just wander around touching each other, like a bunch of rude old men in a sex addiction recovery group. I know, that example is graphic, but it's the only one that really fits.
If you see Sit Down, Shut Up appear on your television set (or flat screen for those of you living in the 21st century), stand up and leave. Or better yet, draw your very own stick figure flp book cartoon and send it in to Fox. After seeing this show I'm sure they'll cut you a check.