I craked the screen of my iPhone?

And i don't know what to say so my mom because she will get mad at me

That's y you Don't get an iPhone! I Don't know y everyone gets them. THEY ALWAYS BREAK!

Say its just the screen prank app

Well you didn't take care of it, and I'm guessing you dropped it on cement. I would downgrade you to a regular dumb phone until you are old enough to take care of things.