For once, it is a mod that has amazing butt jiggle. The effect was accomplished the through hex editing the file that controls Jill's jiggle-bones. I will try to adopt their technique and apply it to my mods in the future, as I have always omitted butt jiggle due to it looking bad (jiggling inwards unnaturally etc). Today, Skyrim modding community is a very toxic place, and most mods are retextures or rehashs of the same old places. Vanilla modding now is the rule. Try to criticize the current "scene" in Reddit, and they downvote-bomb you.