The ins and outs...
Him: Sit your man down on the sofa (not when Eastenders is on, mind!). His feet must touch the floor.
You: Sit on top of him, facing him. Show him who's boss by taking the lead. Lay back on his legs and support yourself on your arms to keep your balance. Open and close your thighs, setting the rhythm yourself.
Why is it so good? You're in control. You decide the rhythm that works for you and discover what you like. You offer yourself up to him and give him a very hot view of your body in action!
A good time to try it: When you're not feeling your best (you're aware of that niggling cellulite, you're bloated or have saggy breasts). Men react to visual stimuli and in this position, all those teeny little flaws will disappear and your body will be akin to that of a goddess, with a perfectly stretched flat stomach, breasts pointing proudly upwards and thighs as toned as an athlete's.
Tip: If he's well wedged into the backrest, he can hold your legs with one hand and caress your clitoris with the other.