A guy who wastes a girl's time by having sex and hanging out, giving all signs of wanting a relationship, but refused to ask the girl to be his girlfriend.
Guy 1: My girlfriend was chumin' me all night.
Guy 2: How so?
Guy 1: when her friends came around she wouldn't even hold my hand and she patted me on the back when we hugged like she's my aunt or something.
when a female is chumin she is currently on her menstrual cycle that consists of dark red blood and chunks like chum (like fisherman use to attract large fish or sharks by dumping buckets of fish blood and guts into the water).