Basically what the title says. He's 14 and we share one room. I don't mind him masturbating, I am a teenager too after all and understand his "urges". But shit. He's doing it in the same room about 3 meters to my right.the worst thing is that he knows that I am not asleep yet. He probably just thinks I can't hear him or something. I already tried dropping hints, for example I started scratching my wooden bed frame as soon as he starts doing it in the hope to make him realize that I can hear him. Is there a way to tell him without making this embarrassing for both of us?

Also: am writing this in the middle of the night while he's doing it and I'll try to get some sleep first and read your answers the next morning. Thanks in advance.

Edit: just wow. When I made this post last night I just hoped for like a few helpful answers but definitely didn't expect this to blow up like this. Well, anyways... Thanks for all the answers. Not only the helpful ones but also those that made me laugh.

Edit 2: what. The. Fuck. I actually just found my post in r/all. The chance of him(my brother) finding this post are actually pretty high now... Thanks again for all the answers and rewards tho. So I gotta go to school for now so I'll (probably) have no time to go on Reddit for a while.