Hook up bag
Bag a person keeps, usually in a car containing a change of clothes, underwear and or toiletries for post sex clean up. Usually the calling card of a cheating partner a Hook up bag can often be found in the trunk of an adulterer for the next time an opportunity arises so they may hide the evidence and wash away the lies.
That girl from the bar is such a slut she keeps a hook up bag in her car just in case.