I fly out. If they're going to make a completely unreal scenario, I'll use a completely unreal solution :)

i think that is the correct answer, reverse the blades and then jump over them so the air current forces you out like one of those indoor skydiving places

Try to dismount the blade from the axle (they're designed to be easily separable, at least in the model I own) and just have the axle rotate and do nothing?

Pleeeeease tell me you’ve actually been asked this question in an interview

No, but it's an apocryphal Google interview question. One of these days I'm actually going to weigh my head (another Google question).

I've gotten a logic riddle that involves scissors and rope, asking what my super power would be, and favorite movie. One that was at least based in math was how many ways are there for a knight to move from the lower left hand corner of a chess board to the upper right without moving back (no left or down moves). Not the DP-solution, though, a closed-form equation.

Get in a pool at the deep end with some floaties and some iron ankle weights. Add floaties and weights until you are at equilibrium at your neck line. Hold your breath and add some weights slowly to your hands until exactly when you start to sink. Drown, but include a request in your will to have them remove your head at autopsy. Have a friend, loved one, or coroner weigh it.