This act requires a man to spread ketchup upon a woman's anus as lubricant before performing anal sex. Then, just before he ejaculates, the man pulls out from the girl's anus and spreads his semen all over the girl's chin. As the semen mixes with the ketchup dripping from her chin, and with the penis as the "french fry", the entire act is very reminiscent of how Canadian's enjoy their fries. Any anal excrement that accompanies the mixture simply adds to the "poutine" only enhancing the experience.
Think you've done some weird shit in your sex life? I had a girl ask me to give her a Canadian French Fry the other night. Damn crazy Canucks.