so all you have to do is pour a drink someone handed you, into another cup.
if you are big enough a douche bag to do that in front of a person handing you a drink, then you would be big enough a douche bag to reject the drink in the first place.
the logic of the cup is completely lost. people wont pay extra for these cups for their parties lol. people who want them would have to use them for themselves and break the usefulness of them.