Blackass follows the story of a man named Furo. One morning, as he wakes up for his new job interview, his normally melanated skin has turned white. As he goes to his interview, he gets a much better job than he anticipated. However, he is missing his family and friends, and life as a white man is harder to adapt to than he initially thought. Furo is homeless, and he is walking around when he meets two people: Syreeta and Igoni. Igoni quickly leaves, and Furo is invited to Syreeta's home for a massage. There, Syreeta notices that he has a black buttocks.
Igoni, now interested in Furo, searches for him on the internet. He contacts Furo's sister, stating that he also has changed. Syreeta and Furo begin having a sexual relationship, and when Furo is invited to meet Syreeta's friends, he notices that they are all married to white men. He also watches an exchange between Syreeta and a man, which leads him to believe Syreeta is trading sex for money with him.
The next day, Furo changes his name to Frank Whyte, and buys new clothes with Syreeta to match his new identity, before he begins his first day of work. Meanwhile, Igoni has changed into a woman named Morpheus, and is meets Furo's sister. He then wishes to meet Furo again.
Furo does well at his work, and is noticed by other companies. However, he doesn't change job to one with a better salary, as he wishes to stay loyal to his company. However, he is promoted to a better job in another city, which he takes, so he can become a new person forever. He has an attraction to a receptionist named Tosin at his work, and when he tries kissing her he is rejected, and called selfish.
He then prepares to leave the city. He goes to Syreeta's house, where she tells him she is pregnant with his child. He lies and tells her he will marry her and move together with her. Furo meets Igoni and they talk. When Ignoi sees how selfish he has become, he calls his family. Furo opens the door for his mother to enter.
