Butt gripping is bad for you and everyone grips their butt. If you need proof just wait until the next time you get annoyed with someone and then direct your attention to your butt muscles and you will likely find a good advertisement for buns of steel. We are a tight assed people and we need to let go of our butt gripping ways. The butt muscles that I am referring to are the gluteal muscles—maximus, minimus, and medius. You can throw the tensor fascia latae in there because of its relationship to the gluteus maximus (and because it tends to be as gripped) via the IT band. These muscles all overlay deeper muscles—the piriformis and the obturators—which can’t function successfully if the muscles surrounding them are in a constant state of engagement or gripping.
When we are standing up correctly the gluteus maximus does nothing (it turns on when we move on an incline or go up and down) and gluteus minimus and medius do an intensely subtle dance of stabilization—searching between them for the balance of internal and external rotation that results in a neutral pelvis. The piriformis which connects the legs to the spine at the back of the body (the psoas connects the two from the front of the body), also helps to stabilize the pelvis in addition to externally rotating the leg. When the butt does its gripping thing—and not to be mean but you are fooling yourself if you think that yours doesn’t—all the muscles around the gripping will suffer, sometimes dramatically. As a people and culture we need to let go in so many ways. Learning to relax long suffering gluteal muscles would be a great place to start.