I totally did that without a harness on a hundred foot ladder one time (not standing on top, but close) so I could attach a camera for an event. No one else would climb it. Now I'm a total wuss and hate even using a step ladder for fear that I'll fall.
Actually it might have been just fifty feet. At least two stories. Anyway, the feeling of being invincible King of the Ladder has a very euphoric feel to it.