Cannon Fuse
The act of screwing a girl doggie style, then taking a burning cigarette or cigar, and placing it in her butt, burning side up. While continuing to screw, wait until the butt shortens, until the burning hot end touches her asshole, and then hold on tight until you explode in her. Hence, when the fuse ends, the cannon went off.
Did you hear about Mike doing the Cannon Fuse on his girl, she nearly killed him afterwards because she couldn't sit all night.