Verb. When something is a sure-fire thing and you screw it up. When a man or woman is interested in going home with you and you say/do something to make them no longer interested.
A streamer on Twitch who has said the n word or is a male and has shown off some skin, because it is against Twitch rules for a male to be sexual on the site. These streamers often move to YouTube Live because they are slightly less SJW.
Where one person (usually female) is not permitted to have an orgasmalone (e.g. through masturbation) unless permission given by their significant other, Master, etc. Often used in D/s relationships. Very hot!
Girl1: Why are you acting odd?
Girl2: I'm so frustrated and can't concentrate. My bf has cum banned me and I won't see him for another month