Rear Entry Sex Position is a just like spoons sex position but on a different way. This position allows the couple to be more intimate. This is a rear entry position, where the guy is on top and the girl is flat facing the bed. The girl can raise her butt just a little bit to allow better access to her vagina and stop slippage.
There are variations in doing this, the girl can either keep her legs closed keeping them both between the guys thigh. This will allow her to have tighter or narrower vagina. This is more prone to slipping, but will hit her G-spot just right. To switch your leg positions and allow deeper penetration, the girl should open her legs and allow the guy to enter her completely.