When I was a kid, my dad taught me a simple, harmless, and effective prank. Just stand on the sidewalk where there are tall buildings and look up. Eventually others will do the same thing wondering what you're look at...which is NOTHING. Well, some guy in New York City named Brett Cohen has pulled off an even more elaborate prank. It's harmless, though, and incredibly funny.

Only in New York. Hilarious.

Check it out.