When my hair was dyed lots of magical rainbow colours, I did used to get this question - mainly from little girls asking nicely, though, so I didn't mind.
My tattoos, on the other hand, have resulted in so very much unwanted handling from strangers - people picking up my arms so they can better read what's written on them, or moving aside bits of clothing so they can see them better. I'm quite a confrontation-avoiding person, and I never know how to deal with these situations - because almost always I think the person doing it thought they were paying me a compliment by admiring them. Maybe I should take a leaf out of Autobot's book and use them as a chance to educate people...
Bookmarks