The rocking horse is a variation of the rider-on-top/cowgirl position. Instead of laying on their back, however, the penetrating partner starts by sitting cross-legged and leans back, supporting themselves with their arms. The receiver then kneels and straddles them.
This variation of rider-on-top can be especially appealing to those who enjoy anal stimulation, as it leaves the receiver's backside free for anal toys like the Hott Love 2.7-inch Metal Heart Butt Plug from Spencer's.