*Though used in Canada, it is not only Western Canadianslang. It is used commonly in the US ranging widely from NY to California since the late 70's (if not before that).
It is also a popular word in the U.K.
Me: What happened to your eye?
John: Mikey and I got into a fight over Cecilia and he snuffed me in the face.
Me: Wait, what? Cecilia that girl you've been dating?
Western Canadianslang meaning to discard in an uncaring fashion. Also means to discredit, disrespect or otherwise judge unworthy of consideration. Likened to throwing something unwanted in the dirt.
Suzy and I were going strong until she up and dirted me one day. I never saw it coming. I'm gonna dirt her to everyone she knows ... payback's a bitch.