Rihanna, Katy Perry, Big Boi Celebrate At BMI Awards Afterparty

Keri Hilson, Cee-Lo, Bootsy Collins also spotted at M2 Ultra Lounge.

NEW YORK — You know it's a going to be a good night when a big, thuggish-looking man with a scar going down half his face comes into the party singing Rihanna's chorus to "Run This Town."

Now imagine being at that same party and the DJ announces that [artist id="1940303"]Rihanna[/artist] is actually in the building. Too crazy. Thursday night in New York City, if you weren't rehearsing for the MTV Video Music Awards at Radio City Music Hall, or part of Raekwon's CD-release show at S.O.B.'s, then you had to be at the M2 Ultra Lounge.

Rihanna Keri Hilson, Big Boi, More At BMI Awards

Rihanna, Katy Perry, Devyne Stephens, DJ Clue, newcomers Jay Fresh Kicks and Jeremih, Keri Hilson, Bad Boy artist Janelle Monáe, Outkast's Big Boi, the legendary Bootsy Collins, Sammie, Goodie Mob members Cee-Lo and Big Gipp, producers Danja, Jim Jonsin and Bryan-Michael Cox, model Tyson Beckford and others attended the Hennessy Black-sponsored event that doubled as the BMI Awards afterparty.

DJ Mick Boogie spun, mixing Young Money's "Every Girl" with Gucci Mane-featuring cuts such as the "Obsessed" remix and "Make Tha Trap Say Aye."

Polow Da Don took over the mic in the DJ booth for a short time, letting Mario and famed songwriter Sean Garrett perform their club smash "Break Up." Mario started off rapping Gucci Mane's part: "Now baby girl had dumped me/ She no longer wants me/ I'm no longer hired, she said that I've been fired/ On to the next one, more fish in the sea/ Girls are like buses, miss one, next 15, one comin'."

The singer then held down his own part of the record, crooning, "Don't I make your earlobe freeze?/ Don't, when I dive, I dive deep?"

Garrett then got on the mic with his verse: "Baby, don't leave me till tomorrow/ Tonight we gon' get a lil' tipsy with a bottle."

When it came to the celebrities at the event, some mingled and some just danced in their own VIP section. Rihanna wore black shades and a black hood and seemed to really be enjoying the reggae. Meanwhile, you could see Keri Hilson walking around in the upstairs VIP, while Katy Perry made her way through the crowded dance floor downstairs.

The 2009 MTV Video Music Awards air live this Sunday, September 13, at 9 p.m. ET, but New York is celebrating the VMAs all week long! Stay tuned for party coverage, concert reports, behind-the-scenes updates and more.