Balancing robot
This wasn't a failure, but it made me laugh...
Somebody on TV was demonstrating a humanoid robot, knocking it's feet out from under it and showing how it could stand -up by itself. After a few times I was expecting the robot to get ticked-off and punch the guy or something! I know it's not programmed for that... It's really no different from stopping a motor with your hand, but I just couldn't help imagining it!