The man on top – who we’d call the “bottom” in other circumstances, since he’s taking his partner’s penis – can sit either facing towards or away from his partner. Obviously, the man penetrating will feel more comfortable if he lies back on the bed as his partner sits on top of his erect penis. Sitting sex is easy! It can develop naturally from a session of kissing and sexual foreplay, or you can move straight into it from any other position in bed as you have sex.