sucker line
n.— «A “sucker line” is when one team seems like it should be a clear underdog but is somehow favored. People place tons of money on the other team. And those people are called “suckers,” because the oddsmakers know something they don’t.» —“U-M fans will disagree, but the sky isn’t falling” by Michael Rosenberg Detroit Free Press (Mich.) Oct. 11, 2005. (source: Double-Tongued Dictionary)