The sex position known as 'Sandwagon' is when one partner is held up by the penetrating partner from behind by their legs --Much like you would hold a wagon, while the held partner is on their hands keeping themselves up.
Imagine a wagon behind held up by the two handles. Now imagine the handles being legs, the wagon being a person, and the wheels being their hands/arms. This is a Sandwagon.
by Magnus Thundercock May 7, 2011