Cheech and Chong carry a metal trashcan down a Los Angeles street to collect gasoline that they siphon from a truck. Then, they pour the stolen gas into a yellow Thunderbird and drive off. As Chong lights a marijuana cigarette, the gas fumes catch fire, turning everything inside the car black. At the film studio where Cheech works, he walks on the lot with his torn, sooty clothes and the guard asks for his pass. He replies he is filming The Towering Inferno and the guard waves him in. Meanwhile, Chong sneaks his neighbor’s stolen Thunderbird back into the garage and replaces the car cover. Cheech returns home in a van. Soon, Cheech and Chong decorate the van with fur on the dashboard and turn it into a low rider cruising vehicle. In the morning, Cheech peers out the window and panics when he notices that the van he borrowed without permission has been stolen. While he figures out what to do, his boss calls to tell him he has the van back and Cheech is fired. At the welfare office, the two friends bypass the crowds when Cheech’s girlfriend Donna, a welfare clerk, processes them in a private office. While Chong waits, Cheech has sex with Donna on the office floor. Donna’s supervisor walks in and breaks up the party. Later, Donna calls Cheech and wants to see him. Cheech tells Chong to leave so he can clean the house before Donna arrives. Cheech gets a phone call from his cousin Red who is visiting from Texas. He persuades Chong to party with Red at his hotel. There, Chong finds Red arguing with desk clerk Pee Wee Herman about the bill. Red misunderstood the hotel’s rates and the clerk is holding his luggage ransom until he pays. Chong and Red break into the wrong hotel room looking for Red’s luggage and interrupt a couple in the middle of lovemaking. The couple alerts the manager who calls the police. Meanwhile, they find the luggage, which includes a duffle bag full of fresh-picked marijuana buds. Chong estimates that Red’s stash is worth $50,000. When several police units surround the hotel, Red tape records the sounds of the police sirens and an officer talking on a bullhorn that he can use later to scare the deer when he goes back home. When the agitated hotel clerk identifies Chong and Red, he is arrested instead. On Hollywood Boulevard, a pretty girl in yellow satin shorts on roller blades invites the guys to a party at an Oriental massage parlor. At the parlor, Chong and Red soak in a hot tub as Chong smokes a gigantic marijuana cigarette. Soon, Red chases a massage girl down a hallway and discovers "Chicken Charlie," a customer wearing a bustier over his business clothes and crowing like a rooster at Candy, a hog-tied massage girl. Chong, Red, and Candy are kicked out of the establishment and as they leave, Red hears sounds of passion from behind a closed door and turns on his tape recorder. However, instead of pushing the record button, he hits play and a riot ensues when the customers and the staff hear the voice of an officer on a bullhorn telling them they are under arrest. Soon, Chong, Red, and Candy pile into a convertible sports car parked outside a music store. The driver takes them to Candy's mansion and introduces them to her mother, who mistakes the guests for trick-or-treaters. Mom invites the guests to dinner and her husband, who happens to be Charlie from the massage parlor, finds them at his dining table. After dinner, everyone smokes marijuana and Red takes them to the Comedy House. Red heckles a comedian who happens to be desk clerk Pee Wee Herman from Red’s former hotel. Pee Wee invites Red on stage, where he entertains the crowd. Before long, Pee Wee convinces the club’s bouncer to toss out Red and Chong. The audience gets pulled into the ensuing melee. Outside, the owner of a Corvette thinks Red is a valet and gives him the keys to the car. Red and Chong go on a joy ride around town. Meanwhile, Cheech has finished his ironing and waits patiently for Donna. He dreams that she dresses in a fur-trimmed red negligee as he approaches her in a snappy zoot suit ready to seduce her. When the real Donna knocks on the door, he yells out in his sleep, “Get out of here.” She leaves and when he wakes he wonders why she hasn’t stopped by. Soon, the police chase Chong and Red through canyon roads and crash their patrol car. Suddenly, a space ship appears and sucks Chong and Red into the sky. Chong, dressed in biker leather, wakes Cheech and tells him a fantastic story about being sucked up by a space ship and offers his friend space cocaine to snort. The cocaine gives Cheech super strength and he crashes through a wall and destroys the neighbor’s house. Fueled by space cocaine, the two friends fly toward a giant animated marijuana cigarette in the sky.