well I just thought that it would be buttocks because the thigh parts didn't match the mesh. But then I thought that if you moved the thighs that some of the buttocks move with it too, like in the fall off zone or something. To be honest I have tried making my last pair of shorts with no buttocks and the mesh just splits between the hips and thigh parts when conformed so I usually add buttocks in. I don't know why it does that, but like I have said before, I really don't know what I am talking about so I could and most likely be wrong.