"Slam Dunk"

I am trying to learn all the American expressions and vocabulary and this is one that I have heard on the TV news recently a lot.

SLAM DUNK = sure thing

"The phrase "slam dunk" has entered popular usage in American English, meaning a "sure thing" – an action with a guaranteed outcome, or otherwise an impressive achievement, in the same way that the baseball-inspired phrases "it was a grand slam" or "he hit it out of the park" was more commonly used in previous years."



"A slam dunk is a type of basketball shot that is performed when a player jumps in the air and manually powers the ball downward through the basket with one or both hands over the rim. This is considered a normal field goal  attempt; if successful it is worth two points. The term "slam dunk" was coined by Los Angeles Lakers announcer Chick Hearn. Prior to that, it was known as a dunk shot.
The slam dunk is one of the highest percentage shots one can attempt in basketball as well as one of the most crowd-pleasing plays. Slam dunks are also performed as entertainment outside of the game, especially during slam dunk contests. Perhaps the most popular such contest is the NBA Slam Dunk Contest held during the annual NBA All-Star Weekend The first incarnation of the NBA slam dunk contest was held during the festivities accompanying an American Basketball Association All Star Game.
Dunking was banned in the NCAA from 1967 to 1976. Many people have attributed this to the dominance of the then-college phenomenon Lew Alcindor (now known as Kareem Abdul-Jabbar) upon his entry into the NCAA. Subsequently, the no-dunking rule is sometimes referred to as the "Lew Alcindor rule."