Everyone has heard of the madcap surreal humor of Regular Show and it's no secret that I rate it very highly, but it's not the first cartoon to do this humor. Earlier than that we had Angry Beavers.

Here is a show about Beaver brothers Norbert and Daggett, one of whom voiced by Sabrina the Teenage Witch's resident cat Salem. After moving out of their family home the brothers find a spot to build a dam and begin there many adventures in the real world but said real world pretty much involves everything older teens are supposed to do in this situation which is goof off.
The cartoon showcases their many surreal adventures which consist of space travel, B-Movie nightmares, becoming discostars and becoming hipsters with their stupidly long teeth; now some of those plot points sound similar to Regular Show and you'd be right.
These days many of the pop culture images and completely absurd plots in Regular Show wouldn't be acceptable ten years ago but the Angry Beavers were doing just that, the only major difference is time. You see the 90s was very much an era that never had it's own running theme so anything went back then.
If you want to bring back disco, make B-Movie horror films seem awesome or collecting cereal boxtops for a street sweeper, then the 90s was the right era for it. Heck even a stump with a drawn on face was considered a major character in this cartoon.
I don't rate it as the best cartoon, in fact it even missed my top 100 cartoon list but I do however rate it as one of the most important. You see an "anything goes" premise can only work when you embrace it as the normal and Angry Beavers was one of the first shows to work with that style and succeed; granted there were earlier cartoons like Ren & Stimpy and Rocko's Modern Life both of whom equally weird but those two function on a different concept.
So that's Angry Beavers; you know I can't help but laugh at the amount of beaver quotes this show had; my personal favorite is still Muscular Beaver.