At the 01:10 mark in the 12th episode of the 7th season of Beavis and Butt-Head, "Citizens Arrest", first aired in 1997, they are at Burger World as a robber comes in and takes out his gun. Just before this happens, they cut from the overall shot to a close-up of Beavis and Butt-Head, and linger on this up-close shot far too long, as the boys look amazed by the gun which is never actually shown to the viewers. When it cuts back to the wide shot, the gunman has just put the gun back into his jacket, covering it entirely.
The gun is never shown to the viewer.
Granted there is no law saying that they have to show this, just because it's in the scene, but the scene strikes me as very unnatural and odd every time I watch it. I suspect it's some kind of self-censorship.