I used to shoot hoops with Gary at the Boys and Girls Club by Park, often until the janitor kicked both of us out on Saturdays.
The basket was a few feet off the wall and Gary, not being the tallest in the class, would run at the wall, then walk up the wall in apparent defiance of gravity. When he was high enough, Gary would spring off the wall to a point just under the rim. Then he would dunk it.
Nothing less than amazing. He was probably the best athlete in the school. And a really nice guy. Condolences to his family.