Beavis and Butt-head vs. the Vending Machine - S4-E28
Other mistake: When Butt-head is purchasing the pork rinds from the vending machine, he notes that the selection for them is F2. When he is pressing the buttons to dispense them, he presses the F button twice, but never the 2 button. Somehow, the machine still dispenses the correct item.
Bradley Buzzcut: Shut up or I will kill you. Do you understand? Shut up or I will physically kill you.
Trivia: Mike Judge once received an angry phone message from a fast-talking man. The man seemed to be complaining about "Beavis and Butthead", although he mentioned a "Porky's butthole". His voice later inspired the voice for Boomhauer on "King of the Hill".