For example, you put a piece of paper or a few peas into a black plastic tube. When the tube is turned upside down, water comes out, and the pieces or peas disappear. A popular trick for the locals, for silencing "know-it-alls," or just for fun...!

Regulars’ table version made of plastic.

The tube is 5.5 cm long and has a diameter of 2.3 cm.