Lil Boosie -- Lean Has 'F***ed Up' Rap Culture -- I'm Glad It's Going Away

Lean is a great-tasting way to DIE ... this according to former addict Lil Boosie, who tells TMZ he SUPPORTS pulling codeine cough syrup from the market ... because it will save lives.

Boosie tells TMZ he nearly died 3 or 4 times from drinking lean and says it's "f***ed up a lot of rappers and the culture of hip hop." He says users don't realize something that tastes like Kool-Aid can be so addictive.

Boosie was reacting to the story we broke ... that Actavis is ceasing production of its high-end cough syrup because it's being widely abused to make lean, also known as sizzurp.

The rapper -- who tells us he's clean now -- spent 5 years behind bars on drug charges, including time for trying to smuggle codeine syrup into prison.

He adds, "Once you on, it's hard to get off ... it's damn near impossible."

Boosie and Nancy Reagan. Who knew?