How do you get Britney Spears to sing you Happy Birthday? It's a simple two-step plan!

Step One: Make a billion dollars.
Step Two: Pay her a billion dollars & throw the biggest, most lavish, celebrity-filled party Las Vegas has ever seen!

That's what one Chinese billionaire did on Saturday night! The enigmatic Jay Lo reportedly rented a space at the foot of the Wynn Hotel, put in couches, a tent, and even a ferris wheel, and invited more A-listers than the first 10 pages of the phone book!

Celebs in attendance included Leonardo DiCaprio, Kanye West, Kim Kardashian, Bradley Cooper, Zach Galifianakis, Jamie Foxx, Tobey Maguire, Ludacris, Robert De Niro, and Chris Brown.

You know, just to name a few!

We know what you're thinking - pics or it didn't happen! Oh boy do we wish! Unfortunately photography was strictly prohibited! One party-goer said:

"Security was matched only by what you would imagine from the Secret Service. Guests and celebrities understood photos were totally off-limits."

So don't expect to see any twitpics of the star-studded event! Just make a billion dollars and throw one for yourself!