What should I tell my parents?

Ok so I just started listening to a band called Blood on the dance floor and now I really want to get some shirts and stuff. But the thing is my parents dont know that I listen to them because im sure if they find out they will be really mad since most of the lyrics are really sexual. My problem is I want to get a botdf shirt and I dont know what to say. Im afraid if I ask them they will ask a bunch of questions like who is this band and let me hear some of their songs. Then id pretty much be screwed. What should I ask them? And if someday they do ask about them what do I say? Im 13 btw