Another idea for purgatory:
You're queueing for your plane, obediently waiting for your boarding group. Your boarding group number is an 8 rotated 90โฐ.
You sit, charging your phone, for the rest of eternity.
Idea for purgatory: you're at baggage reclaim and there is an endless stream of all the luggage in the world except yours. And that's it. For the rest of eternity.