Okay, I’m impressed. Also, HOW DID THEY DO THAT?
See the piece of paper/cardboard on the table behind the glasses?
The way you do this is that you fill one glass completely full to the rim, then set the paper/cardboard on top so it sticks to the top layer of the liquid (surface tension). Then caaaarefully invert it onto the other glass (partly full) and slide the paper out from between them.