A Pythagorean cup looks like a normal drinking cup, except that the bowl has a central column in it. It was supposedly invented by Pythagoras of Samos (yes, that one). It allows the user to fill the cup with wine up to a certain level. If the user fills only to that level, the imbiber may enjoy a drink in peace. If, however, the user gets greedy, the cup dumps all the wine into the unfortunate victim’s lap.
Pythagoras sounds like a real asshole.