This was just posted on Celtics.com:

What started out as a joking bet between Brian Scalabrine and Gerald Green turned into one of the one of the craziest things you'll ever see after practice, and if it could be replicated, a first ballot Hall of Fame dunk contest winning slam.

Scalabrine and Green were talking about dunks after Tuesday's practice wrapped up, and Green jokingly threw the ball about 30 feet up the wall behind the basket and watched it drop to the floor, measuring with his eyes where it landed. After Allan Ray tried the same thing, Scalabrine told Green he'd have three chances to convert the dunk off the wall for $100.

Standing behind the three point line in the right elbow area of the court, Green tossed the ball off the bottom of 1986 NBA Championship banner, which hangs about 35 feet over the floor, and when the ball came back to the floor, Green elevated from just outside the free throw lane, caught it off the bounce with his right hand, grabbed the rim with his left, and tomahawked the ball through the rim, sending the gym into hysterics.

Scalabrine just fell backwards to the floor while Green walked out of the gym slapping high-fives with players and media members.

"You cheated," said Scalabrine. "You grabbed the rim."

"I would have hit my face on it," replied Green.

Sadly, there is no video footage. You'll have to take our word for it.