All shocks get pushed on from both sides. There's a force being applied to one end, and an opposing force on the other end. If one of those forces is missing, it's because your shock has nothing attached to it at one end. Now, what I think you really mean is that both ends are attached to parts of the suspension that pivot, perhaps a 5-bar linkage of some sort? The shock would act as a loaded frame member, or it could be leveraged by two separate arms or walking beams. I can see something like a three-shock system, where twin shocks [or one spring and one damper, or two dampers] above the rear axles compress, allowing a scissor-action on a third shock in front of the seat tube or whatever you would use for a pivot point. This abomination would give that third shock the squeeze for sure. Christ, that's ****ing ugly.