Oh, yes, I've done it.
The sad thing is, I've done it multiple times. And on the same batch. How dumb to you have to be to not put a clamp on it after the second time?
And then, during batch sparging as well. Same batch.
Last week, I managed to get a totally stuck mash and dislodge the false bottom. here's the thing, though- it was SCREWED into my keg MLT. I still don't know how I did it. I guess it's my brute strength.
I have a good friend who says about himself, "It's a good thing I'm so good looking because I are stoopid. Wicked stoopid". I could say the same thing about me.