I have peirced my arm, but I need to tell my mom, how do I do it?
are you serious?! your arm?! wow... that's weird...
well, basically, your mum has nothing much to do but remind you not to overly expose it or somethin... she'll eventually agree with it so just tell it to her upfront before she discovers it that may make her more mad at ya... :-)
first you should take the stupid thing out because its not a permentnt piercing anyway its a surface piercing just take it out and tell your mum you were an idiot and decided to peirce your arm for whatevere reason
say 'Hey mum, I got my arm pierced'