I keep getting boners in the school showers :( help me please

Everytime after gym class we have to shower. Im 15 so i guess im horny 24/7. Theres hot guys butts everywhere & you can see their holes with water running down them. I immediately start to get a boner & fast walk out before people notice.I try to stare at the wall but i cant do that forever.How the fuck do i overcome this please help thank you :)This is so embarrassing but i need help so badly