Purple drank is a slang term for a recreational drug popular in the
hip hop community in the southern United States, originating in Houston, Texas.
Its main ingredient is prescription-strength cough syrup containing codeine and
promethazine. Cough syrup is typically mixed with ingredients such as Sprite
soft drink or Mountain Dew and pieces of Jolly Rancher candy. The purplish hue
of purple drank comes from dyes in the cough syrup.

There are numerous slang terms for purple drank, including sizzurp, lean, syrup,
drank, barre, purple jelly, Texas tea, and Tsikuni.

New Orleans rapper Lil' Wayne has publicly acknowledged his use of purple drank,
and his lyrics frequently mention drinking purple drank. In the Duffle Bag Boy
music video he can be seen holding a Styrofoam cup with "RIP DJ Screw" written
on it. In his freestyle to "Throw Some D's" on his mixtape Da Drought 3 he claims
"I'm not a rookie, I'm a pro..methazine fiend" as well as stating "You know what's
in my Styrofoam...what? S-Y-R-UP." He also mentions the substance in the track
"Barry Bonds" from Kanye West's Graduation album, saying "My drink is still
pinker than the Easter Rabbit," an overt reference to the color of the beverage.
Wayne makes a similar reference in DJ Khaled's song "We Takin' Over."
On March 15, 2013, it was reported that Wayne had been admitted to the
Intensive Care Unit at Cedars-Sinai Medical Center in Los Angeles after being
discovered "shaking uncontrollably" and "unconscious". Doctors found a high
amount of codeine in his system and his stomach had to be pumped three times.
He was said to be in critical condition. The rapper's associates were quick to
deny rumors that he was near death, and he was released on March 18.

source: Wikipedia