Story is by a friend of mine, I wasn't there.

Their DM allowed for fumbles on skill checks and was always rolling the PC's skill check in secret.
Rogue has unknowingly fumbled a UMD check on a gate scroll.

Let your imagination dwell for a second on the infinite possibilities...

This guy, disappointingly, went for the classic "sucked into the void" option.

What would you have chosen?

I myself, was always partial to the positive planes "gain HP until you explode" theme.