A soloist who holds the guitar in an upright position and plays an outrageously fast solo by tapping the fret board, as if he was stroking his upright penis. Hence the term "cock rocker."
When you shoot a load of semen across the room by holding onto the base of your penis while you ejaculate and then releasing your grip 2-3 seconds after cuming.
Joe shot a cockrocket across the room at maxium velocity after and intense sexual encounter with his wife.