The Teen Titans, after being let down that they cannot watch a Rated +45 movie at the local theater, return back to the Titans Tower where Cyborg decided they can play something "stupid" to take their minds off of things. Beast Boy ends up eagerly volunteering to play "Random Animal Rally" which involves Beast Boy turning into random animals suggested by his friends. In the heat of enjoyment, after transforming into several different species of animals, Cyborg accidentally says the word "man", which Beast Boy listens and transforms into.
Cyborg becomes aghast with Beast Boy's new form, with Beast Boy himself finding the situation to be funny. Beast Boy laughs at his own reflection. Despite being poked fun at by Cyborg, Starfire and Raven, Robin realizes that Beast Boy's new form will allow the team to take them all to the movie theaters, and they can now enter the +45-rated movie they couldn't get into before.
At the movie theaters, with smiling Titans in toe, Beast Man approaches the ticket booth deepening his voice to sound more like a "man" requesting the staff member for tickets to the "Death Toilet 3". Without any trouble, the tickets for all five of the friends are easily given out, with a happy Beast Man grabbing them and running to the movie with his friends. Later, inside the theater, the movie comes to an end with satisfied titans and a Beast Man. The friends come to consider that being an adult isn't too bad after all, and with Beast Man around, they can explore what other possibilities they can get away with.
The Teen Titans head into town to do their crazy activities and they first run into a pizza-truck, where Beast Man was easily able to pay a lot of pizzas, thanks to his credit cards. Next, they all go to rent a car. Thanks to Beast Man again, he is able to do it with the help of his driver's license. Following that, they all go to a tattoo shop and all receive tattoos on their bodies. The Titans finally call it a night and return back home at the tower, where Beast Man comments how awesome the night was. Raven warns Beast Man again about changing back to his youthful-self before the "man" comes and finds him and forces him to get a job. Cyborg and Robin don't think a job would be too bad, as everything so far with Beast Man ended up being fun. With that said, Starfire announces she will be heading to bed and wishes everyone goodnight, meanwhile, Beast Man has other plans and says he'll be staying up all night going out doing grown up stuff.
The next day, Starfire finds an extremely tired and messy Beast Man out in the kitchen, where she offers some of her sugary cereal to him. He declines, saying it has too many calories and how he needs to watch his weight. The other Titans come into the kitchen, shocked to see Beast Boy is still an adult, and questions him why he hasn't changed back yet. Beast Boy shocks them again, saying "someone around here has to make a living", where just then his watched goes off and how he is late for work and gets ready to leave. Cyborg calmly suggests for Beast Boy to change back to himself, where Beast Man snaps and denies that he won't and how his "kids" better have all their chores done by the time he gets home from work. Once Beast Man leaves, Raven comments that Beast Boy has gone to the "dad" side and the "man" must of gotten to him when he was out last night. Robin taking in what Raven says, says they better follow him. The younger Titans end up following Beast Man at a office building, in line with other very similar adults waiting to be let inside. The Titans end up sneaking inside the facility disguising themselves as an adult in work clothes.
Once they got in safely, they find out that Beast Man is being mind controlled by The Man. Beast Man's friends devise a plan to get him fired, so he can be free from The Man's control, which ends up being a mean drawing of The Man snuck into Beast Man's work pile. The Man sorts through Beast Boy's work and locates the drawing as an error. The Man confronts Beast Man on his mistake and says he will have to fire him, only ironically to be actual fire burning him. Before that can happen, the Titans intervene and reveal they are in the building and engage in battle with The Man himself. Using his technology, the Man was able to create some office objects to come to life, and proceed to attack the Titans. The Titans end up redrawing, and taking Beast Man with them where they regroup inside a cubicle.
Robin comes up with a plan to combat the Man, and does what "teens do best". He exits out of the cubicle and pulls out an iPod and turns up his music real loud with headphones on. The Man questions Robin what he is doing with no response as his music is too loud to hear his words. Cyborg and Starfire talk by communicating in "teen" phrases that makes nonsense while texting on phones, irritating the Man. He then finds Raven who is reading a teen magazine, where the Man says to stop reading that "garbage" and for her to do something with her life. Raven casually says "whatever", and shoots up her magazine in the Man's sensor, causing another error and causing the Man himself to malfunction and break.
With the destruction of the Man, Beast Man along with all the other adults are no longer being controlled, and instantly Beast Man transforms back into his younger self known as Beast Boy once again. Beast Boy happy he has his hair back, jumps into the arms of his best friend Cyborg who is happy to have him back, and comments that being an adult was terrible, and how he never wants to be one again.
- Beast Man (debut)
As an adult, Beast Boy becomes taller and lankier, losing most of his hair on his head, giving him male pattern baldness. He has a more pronounced chin and wider nose. His eyes are white with no pupils. He has the same green skin color that Beast Boy has.