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.
Beavis: Hey Butt-head, is it normal for the inside of your bunghole to itch?
Butt-head: Beavis, it's not even normal to ask.
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".
Crisis Line - S4-E27
Question: Why did Mr. Van Driessen only give Beavis and Butt-Head one phone?