What's the funniest way a dice roll completely ruined (or saved) your game?

We've all had that one moment where the dice absolutely disrespected our plans or somehow turned a disaster into a legendary story.

One time, our rogue tried to sneak past some guards rolled a nat 1 and instead of just failing the DM ruled that he tripped, accidentally threw his dagger and stabbed himself in the leg. Cue the entire party watching in silence as he tried to explain to the guards why he was bleeding out in front of them.

On the flip side, our bard once tried to seduce a dragon as a joke and rolled a nat 20 and somehow, the DM just went with it. That dragon is now an NPC ally who occasionally sends him love letters.

What's your best (or worst) dice betrayal story?