Lean is a mixture of the following formula:
Promethazine/Codeine Cough Syrup (only obtained by a Rx)
Original Sprite
"and jolly ranchers at the bottom!" - A$AP Rocky - Kissin Pink
All in a styrofoam cup -- double cup it to add some style!
The Purple in "Purple Drank" comes from the Cough Syrup in the mixture. Codeine, an addictive, opioid substance, is responsible for the feeling associated with drinkin' lean. Effects include warm euphoria, mind slowing down, drowsiness, lethargy, and dissociative feeling from the body.
There has been some controversy on what "lean" actually is. Swerve, commonly confused with lean, is Robotussin containing DXM. One rule: lean must contain Promethazine cough syrup with codeine.
This addictive substance has been glamorized by modern trap artists and rappers. Rappers condoning the use of a particularly addictive substance is controversial, and many kids look up to these rappers. They got millions in the bank, livin' the hottest lives, got the baddest chicks, and are drinkin' lean while doing it! Lil' Wayne was recently hospitalized due to a Lean OD, but he's still sippin'. Rappers like Lil' Wayne, Mac Miller, A$AP (Crew), 2 Chainz, and practically most rappers in the modern game glamorize lean as a lifestyle.
"I got codeine in my cup! You bet your ass I'm sippin" - Mac Miller - Loud
Put it all in a styrofoam cup and enjoy. The codeine is mainly responsible for the euphoric feeling after drinking lean. Promethazine causes motor skill impairment, lethargy, extreme drowsiness, as well as a disassociative feeling from all other parts of the body, specifically the stomach and digestive system. If it doesn't have promethazine w/ Codeine, it isn't real sizzurp.
Lean music in trap usually tries to emulate the slowed down feeling they get - bpm is usually 70-110bpm in these songs, most trap songs are around 130-150bpm. These songs are more experimental, less "in-your-face", more singing, transformed lower voices.
From a young dude's perspective on the stance of lean in trap music, the lust for lean definitely outweighs the controversy that it deserves. Many kids look up to these rappers' success, and attempt to emulate their style and sip lean, potentially getting addicted to the substance. Though I don't fully agree on sippin' lean all day, I love what it has done to the creative side of trap culture, and some of my favorite songs are solely inspired by sippin' lean.