I had no idea what a "Calcutta" is, but a quick Google turned up this Wikipedia page:
"Bidding for each contestant begins in random order, with only one contestant being bid upon at any time. Accordingly, participants (originally in Calcutta, India, from where this technique was first recorded by the Colonial British) bid among themselves to "buy" each of the contestants, with each contestant being assigned to the highest bidder. The contestant will then pay out to the owner a predetermined proportion of the pool depending on how it performs in the tournament. While variations in payoff schedules exist, in an NCAA Basketball tournament (64 teams, single elimination) the payoffs could resemble the following schedule: 1 win - 0.25%, 2 wins - 2%, 3 wins - 4%, 4 wins - 8%, 5 wins - 16%, tournament winner with 6 wins - 32%."
http://en.wikipedia.org/wiki/Calcutta_(gambling)