The “stuffing her own panties in her mouth to muffle her screams of pain and/or orgasmic delight” is a common porn trope in mainstream and BDSM porn alike. But when you actually see it performed, it’s usually a half-hearted affair, quickly abandoned. Which is why I assembled this triptych of details from the serious-as-a-heart-attack BDSM site (where nothing they do is half-hearted):

panties in her mouth

That’s the lovely Penny Lay getting her panties stuffed into her mouth to muffle her squeals during a heavy whipping shoot in November 2017.