My brother has a showering problem?

I shower everyday and straighten my hair daily and im a 15 year old girl but my little brother who is 11 shower like every 3-4 days! sometimes once a week. I know its pretty nasty, but im the only one who enforces it. Like my mother showers daily and she dont care when he showers cuz she goes to work early and come home late at night. My 14 y/o brother do admit he stinks but he said it doesnt bother him and hes always not at home anyway so he doesnt smell the stench. I have to like force him to get into the shower and he has short hair so it doesnt take him long. It is getting to be a problem because honestly he stinks. He also DOES NOT wear deodorant. I bought a cool soap kit for him but he broke it, I told him he will get Aids but he said what the *censored beep* is Aids?, I told him if he wants to get a gf his reputation starts now; he said idgaf! I cant even sitinthe same room with him! How can I force him to shower daily or atleast every other day. When I ask him nicely to get a shower he will just say no and and make up excuses. He also has the time! He sits around and plays video games and watches tv!