This is the relevant reference from the Books where Which-Cup is mentioned.
I make no pronouncements on these matters, but report them as I find them.
Arrive at your own conclusions.
I wish you well,
Two tables were devoted to the 'Which-Cup?' game, in which one guesses beneath which of three cups a tarsk-bit may be found. Once the tarsk-bit is placed, the cups are rapidly shifted about, making it difficult to determine beneath which cup the tarsk-bit now resides. A skilled game master can, by sleight of hand, should he be so minded, remove the tarsk-bit from the cup and, if challenged, seem to retrieve it from beneath a different cup.