Perhaps OP found a dead fly, put the crown on it, and then propped its corpse up to serve as entertainment for the gawking masses.

It happened to me twice, once I found a fly perfectly standing still and I was trying to scare it away, but it was dead somehow.

The other time it happened, I ko'ed a fly by hitting it in mid-air with a flat book, it stopped moving, so I picked it up and put it on my desk with pride (it's hard to do). However after five hours it went back to life and started to walk away quickly & fell out of the desk, i freaked out xD