Let's see... do you use the coins for your hotel?
Or...

It is a dueling system where one duel takes place at a time. The first two start, then the winner stays. They other players who did not just lose bid coins on getting to duel the winner. You can also bet coins on who is going to win a match. There are different areas to give coins and receive coins, which will be guarded by EvilMike or the administrator.