You will need:
A clean 1.5 litre plastic bottle with lid.
A jug of water
A drawing pin
Fill the bottle with water right to the very top and twist on the lid.
Carefully, use a drawing pin to poke a line of five or six holes about 2.5cm from the bottom of the bottle. You might need someone older to give you a hand with this step. A small amount of water will come out as you poke hole but don’t worry! Give the bottle a towel dry when you’re finished.
Carrying the bottle by the lid, place it where it’s most likely to catch the eye of the person you’re pranking. When they open the bottle, water will spill out the bottom!