Saw this on the ESPN home page:
The Boston Red Sox will hold "Celtics Night" at Fenway Park on June 22 (the night before the possibly franchise-altering 2016 NBA draft). The Red Sox will honor the Celtics' 1966, 1976, and 1986 championship teams. The first 1,000 people to purchase tickets to the game receive a Celtics-themed snapback hat with a green "B" on the front of the cap.