depends on your tolerance for pain... I have a very high tolerance, when I was getting my first tat there was a guy getting his nipple pierced and he passed the F**k out... LOL... i was like OH SHIT!
I had pierced my tongue, my belly and decieded I'd pierce my nipple just for shits and giggles and to see what the pain was.. yea, I'm weird like that but I was a tad bit curious.
My best friend had her's done but had it numbed when she had her implants inserted and the doc pierced them at the time of surgery... lucky bitch... lol
I decided to seek out a good person to do it that I felt comfy with... well... still didn't feel comfy having some weird random guy holding my nipple in his hand with drool dripping on me a tad bit comfy, but he checked out and all... all..
It stung a bit, tolerable, and was quick... sore for a few days but nothing that I couldn't deal with.
But then again... it is all in that particular person's tolerance for pain.