I caught my 15 year old-step daughter masturbating. She was doing laundry, which is weird in and of itself, and I walked past the laudry room. The door was closed for some reason and I opened the door to see what was up and there she was wearing a pair of white shorts and a T-shirt with her pussy pressed against the side of the drier which was humming along. I stopped dead and backed out but kept the door open a crack so I could watch. She was gripping the drier and grinding her pussy against it and was softly moaning. Her knees buckled a bit and she death gripped the drier and a shelf next to it right above her head as she obviously came. I heard a couple grunts over the sound of the drier which made me hard as fuck. I watched as her body relaxed then closed the door and snuck out of there. A few minutes later she walked by me upstairs redfaced and looking sheepish.

Since then I've tried to catch her doing it again hoping to either enjoy the show or maybe just walk in on her in mid orgasm just to see her reaction. I'm not interested in doing anything sexual with her but it was fun watching her cum.