Justin Bieber -- I Wanna Be The Double Cup King

Justin Bieber wants to be the Donald Trump of Double Cups ... the Sultan of Sizzurp ... because he wants to go into business to create his own line of signature styrofoam cups ... TMZ has learned.

Sources close to Bieber tell us ... the boring styrofoam cup -- which has been around since the 40s -- has become the container of choice for lean ... and Justin thinks it's a cool money-maker.

Sources tell us, Bieber has a special affinity for styrofoam because he loves to doodle on them, and that will be the inspiration for the line of cups with the JB logo.

By the way ... Bieber isn't the first person to jump on the styrofoam train. Rick Ross and Soulja Boy both have lines of cups with their monikers.