Before Kobe Bryantmade his legendary mark on the basketball court, he made a pretty baller move off of it.

He was 17 and getting ready to graduate from Lower Merion High School, in the Philadelphia suburb of Ardmore. And although the top-rated high school basketball player in the country had an upcoming NBA draft to think about and had just signed a $2 million Adidas contract, first things were first: Finals, graduation, who to take to the senior prom...