I have something close to that. I like masturbating near people.
I take my laptop and rub it on my crotch while tabbing through some lewd doujins or ero manga, with my back to a wall. As I gently rub the base of the laptop on my erect penis (or sometimes the edge of it if i am sitting upright), I cum right in my pants while there are people around me. I've done this many times while my siblings, parents, or guests are around.
I get worried sometimes that they might have a good enough sense of smell to notice the semen, but it never makes a stain through Jeans, and I can't smell it myself. After that, I just take a shower since I don't want to have all that cum dry up in my pants and underwear.