While screwing a girl doggy style (traditionally through the Tradesman's Entrance, but vaginal penetration can be an unofficial variation), the male takes hold of the girl's hair (like a horse's mane, or saddle reins) and proceeds to shout out the name of the girl's sister (or best friend) in mid-thrust. The male then grips the hair even tighter and sees if he can hold onto the subsequent bull ride for 8 seconds.

When you eat dirt for the first time and leave your family to build a shack in the woods