I'm tattooed damn near all over, and I can safely say that the ribs were far and away the worst for me. Way worse than the ass, spine, kneecaps, and feet.
Listen to what Killercook76 says in the post above this one. All of it.
But hey, you're 16, and as such, probably don't give a shit what a bunch of old strangers on the internet have to say.
Signed,
An Old Stranger on the Internet