In Cantonese, a person with androgenous genetalia. Usually used as an insult, but is also traditionally used given as a middle name to children when they are born with the condition, as a warning to future sexual partners.
(Hot girl running out of the bedroom at a party) "OMG he dropped his pants and he was so Sen Wei!"
sen up its another word of saying you’ll beat their ass, which can also mean you’re hard and that you don’t give a fuck about anything you do and you’ll run their shit.