The Wet Head Challenge:
The Wet Head Challenge is going to take some planning and a possible Amazon purchase, but it does look like fun! It has a similar concept to the Pie Face challenge, but for this game you fill a hat with water, add stoppers to all of the slots and take turns wearing that hat and pulling the stoppers out. Some unlucky fool is going to pull a stopper out and water will go dripping all over their head. The person who stays dry, wins!
Example here:
(video here)
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Have fun!