I agree she's probably not asking the right question. If you're really open to discussing it or enlightening her/him then ask if they mean something else and then tell them. Then they won't have to ask anymore.
The below bit is my personal
opinion and I hope it's tactful enough not to get me in trouble -
As for prejudice.. I'm sure there are many people who very much are, but some aren't so much prejudiced as wary. When I was younger it was mostly a certain group of people who were pierced and tattooed. People often feared them and stereotyped them to be druggies, troublemakers, etc. I doubt they caused anymore trouble than anyone else in reality, but fearing what you don't know and don't understand is a common emotion. It's partly human nature and part common sense and probably partly what has kept us on the planet so long.
My 80 yr old parents would cross the street to avoid a person with tats and piercings, but I'm 57 and it doesn't bother me although I do notice it (which is maybe the point) and wonder why on earth anyone would do that to themselves. No need to answer that because I know..I just disagree that it's attractive.