She must

"I don't really want to anymore, but my father will kill me if I lose that credit card." sighed Jill.

Jim and Rick had expected something like this, and looked at each other with slight grins.

"Okay, keep playing then. What are you going to bet?" asked Jim.

"Well, I think my left shoe. I'm not going to bet heavily." Jill answered his question.

"Ehm....but shoes, just like socks, are not inseparable. So either two shoes, or something else." Rick intervened. "Hmm...," said Jim, "you have a point there." The look in their eyes completely missed Jill. "And.. whatever you choose you have to put on the pile just like the coins."

"Aah can't I keep my shoes on until we know if I win or lose?" Jill begged. "No, those are the rules. Sorry Jill!" said Jim