What is your favorite bug in a video game that made the game funnier or felt like a feature?

One of my favorites is the Skyrim giant launch bug. Giants were supposed to just smack you away, but because of a physics glitch they ended up launching you straight into the stratosphere.
Another one I’ve always loved is Missing No in Pokémon. It was the first bug I have ever seen and used to abuse it always as a kid.
Currently also making a game and when eliminating enemies they lost their clothes which was kinda fun and I'm keeping that haha.

So the question what are your favorite bugs in games?