The mess I leave in her panties

I often wonder what my sister in law thinks when she finds her panties all crusty, maybe even still gooey? She’s not innocent so she must know it’s nut, she also hasn’t mentioned it to anyone it would seem, could she like it? I wonder who she thinks it is ? Her step dad whom she already thinks is a perv? Or maybe the friends of her younger brother, who are also around and have always been caught drooling over her?