slam dunk is a basketball shot in which a player jumps through the air to force the ball downward through the basket with one or both hands over the rim. From time to time, though, you will hear people use the phrase “slam dunk" when they're not even talking about basketball.
Many people use “slam dunk" to describe something they consider a “sure thing." Your friend who just got a perfect score on her book report, for example, might tell you it was a “slam dunk."
