X-5 Unit is a biological weapon that appears in the movie Beavis and Butt-Head Do America. The X-5 Unit's role in the movie is where Dallas Grimes (an arms dealer) steals the weapon. Later, she encounters Beavis and Butthead, when the ATF found her, she hide it in Beavis' pants in order to get rid of it as evidence. She tells Beavis and Butthead to meet her at Washington, D.C. Throughout the movie, Beavis and Butthead were unaware that they were carrying the weapon. The weapon was making Beavis scratch his butt. (later Butthead says, "Your butt sucks!") The ATF believe Beavis and Butthead had the weapon, this causes Beavis and Butthead to be Wanted Criminals. Muddy Grimes (also an arms dealer) was also after weapon as well. Muddy found the boys not knowing the weapon was inside Beavis's pants. Later, Beavis and Butthead it made of to Washington, D.C. and before Dallas can meet with Beavis and Butt-Head to recover the weapon, she is confronted in the parking garage by Muddy, who demanded to know where the weapon is. Later, Muddy and Dallas got arrested by the ATF. Faced with the possibility of a 60 year jail sentence, Dallas betrays Muddy, telling the ATF that he hid the weapon "in some kid's pants." Beavis was masturbating in Mr Anderson's camper. Beavis was thrown out without his pants. Later, Tom Anderson opens his camper door, telling Beavis to take his pants with him, which causes the ATF to go after the pants. The pants are ripped open, with the weapon flying out of them. The weapon, landing safely on Butt-Head's hand, Butthead doesn't know what he has on his hand decided to give it to the ATF. The X-5 Unit is recovered. Tom got blame for the incident and being Muddy and Dallas accomplice. Tom got arrested. Beavis and Butt-head became heroes.
- Beavis and Butt-head never knew what the X-5 Unit was. When the ATF demanded Beavis and Butthead to "hand over the Unit", the boys think the ATF wants to see their penis.
- Agent Bork stated that the X-5 Unit was an incomplete weapon because Dallas stole it while the Unit was being made.
- It is unknown what Dallas wanted to do with the unit, yet from what she was telling Muddy, it could be assumed she was going to sell it to a foreginer at the conference or perhaps just set it off.