People might think that Regular Show is just some random, made-for-kids-and-adults show with no real underlying meaning, but they're wrong. As a matter of fact, Regular Show is one of the most ingeniously designed shows ever. The point o the show is to explore the psychological state of one of the characters. This might take some explaining, but you'll see what I mean.
To start with the back story, Rigby started working as a groundskeeper at a park, like in the show. Due to him being a slacker and an alcoholic (I'll get back to this), was soon fired. Having no other options, he spiraled downward from there, eventually getting into trouble with the law. As part of his sentence, he was forced to attend rehab for his alcohol addiction.
From this point he had a nervous breakdown and now he's undergoing therapy in an effort to find the cause of his alcoholism. After this he developed dissociative personality disorder (aka multiple personality disorder), creating a cast of characters in his mind that each represent a facet of his personality. His subconscious analyzing his issues through these characters is where the show comes in. The show is just this, his fractured mind coping with his issues.
Each of the characters, like I said, represents a part of Rigby. Rigby, as a raccoon, is how he views himself; childlike, naive, immature, short, etc. Mordecai represents what he wants to be; tall, responsible, mature, but still down to earth and cool. Mordecai also in a way harbors some of Rigby's insecurities, including (the obvious one) his insecurity with women. Benson represents the rage and anger that Rigby is holding onto. Benson always being mad at Rigby as a Raccoon could be seen as Rigby's depression, which can be attributed to his alcoholism or other issues. Muscle Man is how Rigby believes the world views him; rude, overly emotional (see: See You There), and ugly. Skips represents the wisdom that Rigby either wants to acquire. Mordecai & Rigby always go to Skips for the answer is a sign that Rigby wants to think that he would always have the answer to any problem he'll encounter (and the times Skips doesn't have an answer is his fears of the realization that he won't always have the answer). The reason that all of these characters are not humans and are instead things like an immortal Yeti, a bird, a raccoon, a gumball machine, etc. is because it's Rigby's way of dissociating himself from the attributes they represent, either because he's ashamed of them (Muscle Man, Rigby) or because he doesn't really see the qualities inside himself (Mordecai, Skips).
From here every episode could be seen as Rigby dealing with an item from his past. To show what I mean, I'll break down an easy example, Don. In the episode, Rigby is dealing with emotional trauma that he received from a brother growing up. Rigby's general agitation when around his brother is more than apparent and is not very effectively explained. The show never really shows how Don and Rigby interacted alone, just how Rigby's friends liked Don. It is easy to infer that how Don treats everyone else and how he treats Rigby in front of people is not true to who he is. Don was probably an older brother that he had who was abusive (probably physically or emotionally), and to deal with this Rigby created a new brother who was a genuinely good brother, but he still had the pain from his real brother acting as a barrier between him and Don. The point of the episode is that Rigby needed to get over the abuse he received from a loved one so that he could, in turn, learn to love and trust people again.
To Be Continued
