1 definition by Blob09

When a guy hits a girl in the face with his penis. This often happens when a girl is giving a guy head. Usually an absurd gesture that a man will do to a promiscuous woman.
Guy: "So i was getting with Cheryl, and I totally cockbrained her!"

Guy 2: "Dude, she's got a shiner now!"
by Blob09 April 11, 2010
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