Well first of all, don't get your bellybutton pierced if it doesn't fit your anatomy. Your outie bellybutton is interesting and beautiful enough without a piercing. You were born with an outie bellybutton because it is a part of you, and you don't need to change that. I have my bellybutton pierced, and I want to take it out, but when I do, I am left with a huge hole in my bellybutton that will never disappear.
get someone to punch you realllllllly hard in the stomach
It doesn't work that way, sorry.
You're stuck with it.
I'm sorry to say but only plastic surgery can help that!
Sorry but unless you plan on spending thousands on unnecessary plastic surgery, it ain't happening.
You can't change an outie bellybutton to an innie. It's a result of how your umbilical cord healed when it was cut off, and is permanent. However, if you want to pierce it, you still can. Here is more information on piercing an outie bellybutton.