College sophomore Jake Schwartz looks up at the red Solo cup teetering dangerously close to the 15-foot ledge above him.
The cup is full of water, and it's attached to his arm by a string. One wrong move and it will dump on his head.
Schwartz tries to be still, but it's hard not to move. The cup inches forward.
Then it happens: about 10 minutes in, his arm jerks and the cup drops, soaking him and his leather jacket – in 30-degree weather.