When someone you see is so basic yet so absolutely hot that they're off the stack/unique in how basic they are.
Isabella: hey my look at this photo of my friend
Fernando: oh my god. Shes like a water from walmart off the stack
Isabella: what the fuck does that even mean
A Cum Stack is a mass of largely agreeing opinions that are discussed to inflate the ego of the ones own ego. Cum Stacking is the act of creating a Cum Stack
Person one: “oh my days the fuck was that work meeting, waste of time”
Person two: “yeah literally , what a cum stack”