Responses
If it yaoi this one I guess.
http://www.mangago.zone/read-manga/kichiku_encount/
Not sure if this is the one, but the same thing happens in this:
http://www.mangago.zone/read-manga/kichiku_encount/
Yeah this was it, thank you ^^,
There's a manga which I'd seen only a page of, but cannot find it anymore. In that page, a guy was in train with his headphones on, listening some "indecent" things and because it's loud, some other guy says that he can hear all of it.