well depends It does depend, you have to look at the characteristics of the person and just think of a name that matches it. I am currently about 5' 3" and slim, I have always been small so my mom...
For girl best friends: "Hey sexy!"(As in jokingly.) Maybe something close to her name? Like if her name a Casey, you could make something like Case Of Cookies? Maybe babe as in jokingly too, skittles...