Happy 39th birthday, Leo! He showed all those Super Sweet Sixteen’ers who is truly the coolest dude in school — inviting Kanye and 2 Chainz to perform at his big bash last night. Either his hard-spending, hard-partying role in Wolf of Wall Street left a permanent impression or Leo’s not about to let the big 4-0 force him to give up his Gatsby-esque revelry. Never let go … of your youth.