1: To be owned by being slapped in the face by the long hair of male.
2: To have long, masculine hair forcibly thrust into one's face.
By societal standards, Men do not traditional have long hair. Frequently, if a man does have long hair, other individuals will make derogatory comments about his hair, despite the fact that he grows it out to donate to cancer patients.
Sepowning is named after a Sir Sepos from medieval Germany. Sir Sepos valiantly wrestled for his kingship, but was looked down upon by other bigger, fatter, wrestlers. Upon the four sided war of 1465, the largest of the German wrestlers, commonly referred to as "Big Zib", or "Zibby", made the mistake of telling Sir Sepos to cut his hair. It had been a particularly bad day for Sir Sepos, and having taken enough ridicule for his long hair, Sir Sepos wrestled "Zibby" to the the floor. Once proving his dominance, Sir Sepos, in his frustration and lack of anything better to do, dangled his long hair in the face of "Big Zib." Meanwhile, "Zibby" cried out in what appeared to be physical pain.
Since the battle between "Zibby" and Sir Sepos, other long haired men have adopted the ritual of quickly turning their head, and slapping people in the face with their long hair, when insulted about their hair.
Jerk: Cut your hair hair! You look like an ugly girl!
Long Haired Man: Shut up, I'm growing it out to give to locks for love.
Jerk: What girl would want your hair? Its gross as hell!
(Long Haired Man slaps Jerk in the face with his hair)
Jerk: Oh my God, that's gross.
Random Person: You just got Sepowned!!!