From the "Poetic Imagery" section of our Dictionary of Semenyms:

body - a man’s physical existence; used to describe an ejaculation of such force that a man’s entire body might be pulled through his cock in the wake of the semen blast. “All of a sudden he felt as if his body were going to explode out through his dick, as if his dick were a cannon and his body was going to be compressed and shot out through his cannon.” —Larry Long