I'd be on YouTube or any kind of app that doesn't even send ads, then for some reason an ad would pop up either sexual or completely irrelevant. It only just started happening recently, what should I do? It'd usually pop-up from play music. Its very disturbing because I am young I dont need to see such sexual ads. Please help
Install Malwarebytes Anti-Malware and let it run (preferably overnight). Then install Kaspersky Internet Security and let it run (again, preferably overnight). Then install Anti Adware and let it run. One of them should catch it. (There's no way to tell in advance, but you should have them all running anyway.)
Welcome to Android Central! Moved from the Android Apps forum to the General Help forum, since the former is intended for developers to promote their apps.
You probably installed some adware alongside some other app unwittingly. Uninstall apps one by one until this behavior goes away.
Incidentally, with all due respect to @Rukbat, you might want to avoid Kaspersky, considering the increased scrutiny it's come under recently.
What browser do you use? When you open the browser, does it take you to a shady page you know nothing about? Try Malwarebytes Anti-Malware as Rukbat suggested to scan your PC for malware. I personally use Firefox plus an addon called uBlock Origin which blocks most of the ads available. Try that, too.
