Most Helpful Girl
I use it sometimes but not to my guy friends. Just family members. :D
And my sister's boyfriend calls his sister that. It's cute.
Most Helpful Guy
I only use the word "boo" when I'm talking to my girlfriends' best friends. I'll be like "My boo..." haha. I feel it's kinda weird if I were to call my girlfriend boo, but if she doesn't find it odd or you don't feel weird about it go for it! Defo don't use it around your guy friends, they'll judge you hard, haha.