Fifty

[Rihanna]

Underground surrogate word for okay. Stems from the 20s and 30s as a positive term for law enforcement agencies cracking down on organized crime and alcohol.

[Monty]

Fifty caliber.. a round of ammunition the bullet of which is a half inch (12.7mm) in diameter.
A common .50 cal round is the .50 BMG (Browning Machine Gun), the round which is (unsurprisingly) designed for the Browning .50 caliber machine gun.
The BMG itself is the large belt-fed machine gun known as a Ma Deuce. It was invented at the time of WWII but has remained in manufacture to this day because it is a very sound and effective design which it would be kinda hard to really improve on.
Now however there are a lot of other guns, including shoulder-fired rifles and even a single-shot pistol, firing the BMG round.
Fifty can also refer to the weapon used to fire .50 caliber ammuntion.

[Britney]

another name for mersh... or the weed one step above shwag... give you a shitty hi that only good if your just doing it to get stoned.

[Kit]

Every womans idea of the perfect guy that shares not only a connection but also the same kinky and sexual attraction.

[Monty]

the cops

[Marquetta]

Fifty dollars worth of marijuana. (usually somewhere from 2 to 5 grams depending on the quality and dealer)

[Luis Fok]

Further shortening of [FFD] (acronym for Fat Fucking Disgrace).

[Renato]

1 a numerical value

2 a quantitative value

3 to split in half

[Justin Bieber]

In [Cork], [Ireland] means your date not [showing] up.

[Tina]

[short] for [fifty cent]

[Luis Fok]

The number equivalent to the product of five and ten; half of one hundred; 50.