A sturdy piece of plastic. You cover the opening of the cup with it and flip the cup. Keep your hand under the plastic for support and the suction will keep the water inside. Then set the plastic right next to the edge of the counter and slide the cup off the plastic and onto the counter fairly quickly (the crack between the plastic and the counter can break the seal so move quick but don’t knock the cup over). Then wipe up the little bit of water trail that’s left behind. To pick the cup back up, just reverse the process.

I went hard on my mom one year in high school. I drew a tiny spider in marker on the toilet paper. I flipped two cups of water upside down on the counter (so the water stayed in them). I searched all of her shoes so they were the left on the right and the right on the left so when she put them on, they’d be on the wrong foot. I taped a sign to the trunk saying to honk at her. I can’t even remember all of them anymore but it ended up being like 13 pranks. The only thing I didn’t mess with was the coffee. And I made sure none of my pranks would actually make her late for work. I did wake up early that day to her scream in the bathroom but I just kind of laughed and went back to bed. Apparently she took one look at the counter with the cups and was like “she’s cleaning that up”. She said she’s did spend her entire first cup of coffee trying to figure out how I got them on the counter without spilling them before she decided she wasn’t awake enough for that shit. Then she couldn’t figure out why everyone was honking at her going into work until she checked the car when she arrived. We got a good laugh out of it when she got home and she made me demonstrate how to flip the glasses and clean them up without spilling using a plastic table mat.