Giancarlo Stanton -- I'm Gonna Spend My $325 Mil Contract On ...

He's 25-years-old ... he just signed the largest player contract in the history of U.S. team sports ... so how's Miami Marlins superstar Giancarlo Stanton gonna spend his $325 million???

He's got some ideas.

Stanton was on his way into Greystone in L.A. this weekend with his crew (we're guessing he covered the bill) and talked to the All-Star outfielder about his complex spending plan.

Check out the clip ... though we're guessing Stanton may have been joking ... based on the fact he popped a $20k bottle of champagne hours after he signed the contract last month.