A hand of
sheepshead which occurs when none of the players opt to be the
declarer/
picker. The winner of a leaster is the player who takes at least one
trick and who gathers the fewest total
points at the end of the hand. Depending on your method of
keeping score, the hand after a leaster is usually valued at twice its ordinary value.
1 On a personal note, I tend to agree with bitter_engineer's writeup on sheepshead; generally speaking, no one likes leasters. However, many people play by a rule that it is impermissible to quit the game immediately after a leaster.
1: Two consecutive leasters comprise a leaster doubler, and the second leaster's point value is doubled. A hand after a leaster doubler is worth quadruple value. The hand played after n consecutive leasters is valued at 2^n times the value of an ordinary hand.