Nothing is perfect! Its not possible. There is always a fault or something that can be improved. "Nine Nine" means as close as it gets to perfect. AKA 99%.

a catchphrase used by the CUTEST groups of humans ever, it symbolize their precinct; the nine nine. it’s their way to show how they are together, forever.

Slang used to say 79th street in Chicago

To do something frequently.

Derives from local television and radio stations doing their traffic and weather "on the nines"

A low income slang reference to a semi-automatic pistol chambered in nine millimeter bullets capable of pricing level 2 armor. The slang originates in low-income neighborhoods or ghettos around the US in cities such as Edina, Chicago, New York, Worchester and others. It is called this because there is often violence within these neighborhoods especially gun violence with the most common weapon being the nine millimeter semi-automatic pistol.

Not the definition of the "girth" of the barrel, but rather it's bore - the width of the hole that goes through the barrel. Also, not coincidentally, the diameter of the bullet - 9mm.

Refers to a pistol, usually a semi-automatic, ostensibly a 9mm.

Aside: The U.S. Army's standard pistol is a 9mm semi-automatic.

A nine is nine grams of cocaine. someone who was addicted would buy that much and do it all day, and not have any left by the next day (if they slept at all).