I was trying to explain to my daughter the other day why I don't let her have personalized items -- backpack, purse, etc., things with her whole first name. Gave her a scenario of sitting somewhere with her friends and some guy sees her name and says hello using her name, and saying "don't you remember me, I know your parents, my feelings are hurt that you don't remember me, by the way I saw your parents over there, I'll walk you over to them, yada yada." Her eyes got kinda big and I think she got it.
You know the private school my granddaughter goes to has their last names on the back of their sweatshirts. I think I will bring that up.