- money made easily or quickly and sometimes unscrupulously: He speculated briefly in the commodities market in the hope of making a fast buck.
Origin of fast buck
Money made quickly and easily and, often, dishonestly. For example, He's all right, but his partner is just out for a fast buck. This expression gave rise to fast-buck artist for an individual, especially a swindler, intent on making money quickly. [Slang; mid-1900s] Also see easy money.