Green’s Dictionary of Slang

(US) money, esp. a first payment or investment.

1972		D. Jenkins Semi-Tough 73: I happened to scare up a publisher in New York who was enthusiastic enough about it to give me a whole lot of what you call your up-front whip-out.
1981		J. Ellroy Brown’s Requiem 11: My fee for a repossession is the sum of the owner’s monthly whip-out.