I saw a Flat Earther doing an "experiment" on YouTube to show how Earth can't possibly be a watery globe. He drenched a sponge ball in water, held it in front of him, then quickly spun it as he let go so it quickly span a few times before falling to the floor. As it span in the air a load of water sprayed off it in all directions. His point was that if Earth was a watery globe all the water would fly off as it span. Somebody should point out to him that Earth spins much more slowly than that ball - it takes 24 hours to do just one rotation. Also, Earth's gravity is much stronger than the ball's.
A well-known Flat Earther for viewers of SciManDan's YouTube Flat Earth debunking channel had a device which measures Earth's rotation. He didn't think it would work as he believed Earth didn't spin. He filmed himself LIVE on his YouTube channel on front of his followers using the device, and as he was using it he suddenly exclaimed "A 15 degree per hour drift!", because that's what the device was measuring. So he accidentally debunked himself and Flat Earth live on YouTube. He's called Bob and whenever SciManDan mentions him on his channel he plays the part of the video on which Bob exclaims "A 15 degree per hour drift!" and then SciManDan always says "Thanks, Bob!"