When you reach Iron rank (10) and have completed the Stakes tutorials, you have unlocked the ability to Snap.

Snapping is a function in a match that allows you to raise the stakes that you win/lose.

In a match, click the cube in the top-middle of the screen when you are feeling confident (or want to bluff your opponent into thinking you will win!).

This will cause the stakes to double on the next turn.

Each player can snap once during a match.

On the final turn, the stakes will also automatically double.

This means that stakes for a match can be either 1, 2, 4, or 8 Cubes!  For example:
If nobody Snaps, the stakes will be 1.  After the last turn, they will auto-double to 2.

If one person snaps, the turn after the stakes will increase to 2.  On the last turn, they will auto-double to 4.

If one person snaps, the turn after the stakes will increase to 2.  If the other player snaps the stakes will increase to 4.  On the last turn, the stakes will auto-double to 8.

You can see what the stakes are in the current match by the number in the cube, both for the current stakes in the middle of the cube and what the stakes will be on the next turn underneath the cube.