n. (kum'runs) When a person has received anal-pounding from a male (of any species) and has had ejaculatry substances dispensed within their rectum (or higher within the intestinal tract, depending on the monstrosity of the perpetrator), the receiver will obtain this diarrhea-like urgency to explosively relinquish the gooey-lovin'.
Those 4 hispanic gang-bangers fucked my ass raw last night, and filled me with their moustacho-man-juice. It gave me the cumruns all morning!
When a person goes out for the sole purpose of hooking up. Similar to a milk run, a woman may get dressed sexy to attract guys and go for a cumrun. Or, a guy gets ready and goes out with the intention of cumming. (then finds someone to do that with )
This girl at the bar is definitely on a cumrun tonight. Shes got on her cumrun dress tonight! This group of guys are definitely on a cumrun tonight, so aggressive!