When a guy and a girl are cuddling, and the only have one pillow, the male should offer the female the pillow and use the female's butt as one, instead. Nice, warm, and comfy.

When two people lie down facing away from each other with their butts touch. Usually after a fight a couple will initiate a butt cuddle, or when they want space to sleep but still want to be touching.

When spooning and a guy gets an erection, usually results in sex