To re-think a bet, having learned new information.
My favorite morning DJ Brother Wease of Rochester,NY, uses tons of slang for differnet reasons. He is a poker addict, and gambling in general.
During the Friday movie reviews, the critic claimed 300 would pull in 25 Million plus! Wease was ready to start a bet, the critic statedd nothing else was opening up. Wease said, he better "back off the window"