Walter Montego: I found this :

A rule often used in money play (but never in match play) which says: A player who accepts a double may immediately redouble (beaver) without giving up possession of the cube. The opponent (the player who originally doubled) may refuse the beaver, in which case he resigns the game and loses the current (doubled) stakes. Otherwise, he must accept the beaver and continue the game at quadruple the stakes prior to the double

rod03801: Thank you rod. An interesting word for a betting action.

We used to use "beaver" to mean someone that watches you play pinball and gets so close to the action that they bother you while asking questions about the play.