In basketball the term D-up is used to prompt defensive intensity from a team or specific player on the court. A player will yell "D-up!" on an important defensive possession to emphasize the need for defensive pressure. To D-up, players are expected to find their defensive matchup, be locked-in, and assume a proper defensive stance. Defenders should have their knees bent, eyes watching their man, and arms out in the passing lanes.
Often times, the term D-up will be used in frustration after a team has allowed an offensive run by the opposing team because of weak defense. In other situations, it can be used to increase the confidence of a player that has been playing consistently solid defense. The term is used by players at every level of basketball and is a recognized form of motivation on defense. D-up can also be used across many other sports but is most common on the basketball court.