Getty Nate Robinson of the New York Knicks attempts a dunk during the Sprite Slam Dunk Contest on All-Star Saturday Night, part of 2010 NBA All-Star Weekend at American Airlines Center on February 13, 2010 in Dallas, Texas. Most friends for life are joined at the hip. For three-time NBA Slam Dunk champion Nate Robinson and his new lifelong friend, Shane Cleveland, the bond runs deeper — they’re tied by a kidney. The former New York Knicks guard, once racing against time as his kidneys failed,