Sandbagging
'Sandbagging' refers to the act of slugging someone on the head with a sandbag -- usually the act of street Apaches, a sneak attack. Hence the application in cards. It actually means to incur a loss on another player (or partnership) by understating your own holding, as in pinochle, when a player or set of partners will refuse to bid even with a good hand to cause the dealer to be 'stuck' with the bid which he cannot make and thus take a penalty.