During the You Betcha! Event, an option will appear before answering the final question of a level that allows you to place a bet indicating that you think you can answer the next question correctly!

If you place a bet and answer the question correctly, you will win additional Coins. If you answer incorrectly, you will lose the Coins that were bet.

If you do not wish to take your chances on a bet, you can tap the "No Thanks" button on the Event pop-up.