Have you seen this prank before? You put a penny under an open bottle of water - toss a towel on it - and claim you're going to make the penny go through the bottom of the bottle, and end up inside.
The whole thing's just a setup. When they stare into the bottle to check, you squeeze it and blast them in the face with water.
There are literally hundreds of videos online of people doing it. But this might be the funniest one. An older lady in Indiana recently did it to her husband and the best part is how hard they both laugh.