Upside down water
Put some ice cubes in a glass and put the glass upside down.
Your guess is as good as ours as to how this person achieved this. We’re guessing either ice cubes in a glass or maybe even wet paper carefully removed.
More April Fool Pranks
This prank is one to build up to April Fools Day. Every time you are near someone leave pennies / small coins without them noticing.
Many people use their smartphone all the time, so one of the best ways to mess with them on April Fools' Day is to mess with their smartphone.
Food pranks are among the best because they're easy to implement, and they generally get a big reaction, especially when someone gets something they don't expect.