To make an apparently inferior bid or play in a deliberate attempt to score a top. You might employ this tactic towards the end of a duplicate session in an attempt to convert a good score into a winning score.
For example, if you were sure that a normal score would be no good for you and that playing a contract normally would result in an average score, you might take an anti-percentage play.
Suppose you have a suit combination of 10-9-x facing A-K-J-x-x. You might cash the ace-king in the hope of felling the doubleton queen offside. You risk a bottom (when the finesse would have worked but the queen does not drop) for the chance of a top.
In the bidding, an example of shooting for a top is bidding a grand slam that you know depends upon a finesse.
