This ones kinda complicated, but some of you might want to try it out - it was loads of fun!
A few years ago we acquired a new employee (rather temporary, as it turns out) who was dumber than dead dog shit. A co-worker and I concocted an elaborate plan to prove just how dumb this guy was.
We took two eggs and punched tiny holes in the bottom and drained them. Covered the little holes with tiny bits of tape and Liquid Paper so you really couldn’t see any difference unless you picked the egg up.
Then my co-worker started a converstion with me (in the presence of the ignorant asshole) about this neat bar trick he had that always won him a lot of money. He claimed that if you shook an egg really hard and fast for several minutes, then smashed it against your forehead, there would be nothing left but shell pieces because the insides would turn to froth and vaporize. I, of course, told him he was full of shit, etc. whereupon he went to the refrigerator, removed an (empty) egg, and demonstrated (ignorant asshole watching closely).
I still carried on about it being impossible, it was some kind of trick, etc., while my co-worker insisted that it was simple and that I could do the same thing. I reluctantly let him convince me to try it, and to reassure me he brought the whole flat of eggs from the fridge so I could select my own egg (the second, carefully placed, empty egg). I followed his directions for shaking speed and intensity, length of time, etc., all the while threatening him with dire consequences if I ended up with egg on my face (literally). Sure enough, my egg crunched on my forehead leaving only shells, and I was properly amazed!
Of course, the ignorant one couldn’t wait to try it himself, and sure enough . . . egg splattered all over his face, dripping in the floor, etc.
Believe it or not, we kept a straight face thru the whole thing, even expressed sympathy for the trick ‘going wrong’ for him, so he never really caught on - I wonder how many eggs he smashed in his face at home trying to duplicate that trick?
Hey, we figured if he was stupid enough to believe it, he deserved the eggy face.
If there is room for doubt - doubt!