Shake your head back and forth. Did you feel like you were making an absolutely insane looking expression? Probably not, but, as you'll see in this video (which would make a great screensaver), viewed in slow motion you would have — most likely, just for a moment — appeared rather silly.
The face-shaker, Will, told Boing Boing: "This is my face shaking, with a thimbleful of water in my mouth, filmed at 1,000 frames per second. Preeeetty gnarly."
Agreed! But also super awesome.