This is a prank that everyone should know. Whether you want to have a good ol' laugh with your mates, or you just wanna turn their drink upside down and piss them off.
Step 1: Fill Up A Glass With Water.
Step 2: Place A (kinda) Flat Plastic Bag On Top.
Step 3: Hold Down The Bag Tightly Around The Sides.
Make sure there are no folds or bends while securing. DO THIS PART IN A SINK OTHERWISE EXPECT ALOT OF CLEANING UP!
Step 4: Quickly Turn The Glass Upside Down.
Step 5: Take The Bag Out From Under It Quickly.