The Spider begins with the couple facing each other in a seated position. The woman lies back, while the man scoots between her legs, achieving penetration. Then the man lies back, careful to maintain his erection inside her. If the position is done correctly, each partner should be lying flat on their back with their head between the others' legs, butts touching.
To improve the range of movement, the couple can bring both knees up so that they each have something to grip during the motions. The couple is now instructed to wiggle, gyrate, and grind their buttocks anyway they like.
This article appears in Feb 17-23, 2010.