The act of reverting back to your animal instincts, and railing a chick from behind. Most of the time, Pulling of the hair and slapping of the ass is included in this primitive form of hardcore rumping.
After a night of heavy drinking, David took his slam piece back to the Frat. One of his bros asked him what they had planned for the night. David responded, "Going Primal BRO!!!"
by TFM-BRO July 01, 2011