NEW YORK -- When was the last time you saw 35-year-old men and women jump up and down like Kris Kross? When was the last time you saw jaded music-industry folk thrust their arms up and down like high school kids at a prom afterparty? And when was the last time De La Soul, Brand Nubian, Black Sheep, Black Moon and Smif-N-Wessun performed together? On Tuesday night, all three occurred at club LQ as Cornerstone Promotions celebrated its 60th mixtape.

The Cornerstone mixtapes, which come out every month, have been a hit in the music industry, as DJs from Whoo Kid to Green Lantern have hosted the CDs (the discs act as a promotional tool for artists and various companies, including Sprite). The party was promoted as a heavyweight industry shindig with members of the Wu-Tang Clan, Talib Kweli, Lil' Kim, Kanye West and the Roots among those supposedly on the guest list, but by midnight the only A-list artists who had showed were Maxwell, Nas and his bride-to-be, Kelis.

That was cool, though. DJ Clark Kent kept people on the dance floor, playing selections from the golden hip-hop era of 1994-96, and unbeknownst to many of the party attendees, many more MCs would be coming through, not just to schmooze, but to rap.

The Cocoa Brovaz, the duo still affectionately called by their former moniker, Smif-N-Wessun, started out the night of "surprise" performances (some members of the press were tipped off about the roster of acts that would take the stage).

Once the bass line from "Sound Bwoy Bureill" dropped, some men started yelling,

"Bo, bo, bo," as they made the symbol for a gun with their fingers and raised their arms to the air.

Cornerstone 60 release party photos

"You can't test the champi-unnn sound/ You gettin' bucked down, recognize my Boot Camp Clik outta Bucktown," the crowd chanted along with the duo as they performed their hip-hop/dancehall hybrid.

"We got a special guest," the group's Tek informed the crowd as the horns from Black Moon's "I Got Cha Opin" remix started to play. Then Black Moon frontman Buckshot came out and started firing off his classic quotables from the song.

"Me and my crew walk the streets at night like looking for the right one, bay-bay/ If it's payday I'm at your doorstep ..." rapped the gravelly voiced MC, who wore a black T-shirt emblazoned with Frank Sinatra's 1938 mug shot.

Buck followed up with "How Many Emcees?" then walked off the stage. Buck quickly returned as the beat for his group's debut record, "Who Got Da Props?," started.

"This is my first song," he told the crowd. "I wanna take y'all back."

"Put up, what up, BO BO BO!" he spewed with ferocity, making the crowd jump up and down. Some of the old-schoolers in the crowd even took their dancing way back, doing the famous project stomp.

After Buckshot and his Boot Camp Clik made their way offstage, the night's emcee, DJ Tony Touch, told everyone to keep their eyes on the stage. C.L. Smooth (his partner Pete Rock was DJing at another gig in New York) then entered and tried to catch wreck, but he had some temporary mic problems and had to leave the stage. When he returned, C.L. made sure his final exit would be on a high note, as he performed "They Reminisce Over You (T.R.O.Y.)" for the finale of his brief set.

Then it was on.

Brand Nubian came out for their set of timeless joints, starting off with fire, "All for One." Save for the wrinkles on the face of the still-fresh-to-death Grand Puba, and Lord Jamar shearing off his signature dreads for a Caesar haircut, the Nubes looked almost exactly as they did back in the early '90s when they had New York on lock like the G-Unit and D-Block do now.

Puba, who was known as one of the flyest b-boys in his heyday, still had his smooth swagger as he set off the first verse with famous lines like, "I gets headaches from the wack/ So then I take a Bufferin and I max."

The Grand Man was given time to shine on his own, with his biggest solo song ever, "360." No one could stop dancing when they heard the Gladys Knight sample of "what goes around come back around again."

"Now big up to my Brooklyn mob," Puba rapped before being answered back with the fervent crowd response of "Brooklyn! Brooklyn!" "Big up to my Uptown mob," he continued, and was again answered by the crowd, this time with "Uptown! Uptown!"

Puba's crew got a chance to rock on their own as well. The second his record was over, the beat dropped for Sadat and Jamar's tag-team effort, "Punks Jump Up to Get the Beat Down." The record could've been renamed "The Crowd Jumps Up to Get the Beat Down," as people's feet started to leave the ground once X and the former star of "Oz" started rapping.

After Brand Nubian, De La Soul came out, but their set seemed too short like Todd Shaw, because after performing verses from "Buddy" and "Oooh," they brought out one of their Native Tongues crew brethren, Dres of Black Sheep. Dressed in a sweater vest and short-sleeved button-up, Dres did his own stirring of the pot with Black Sheep's two big hits, "Flavor of the Month" and "The Choice Is Yours." On the latter, he had even more people jumping with the famous sing-along lyrics, "Engine, engine number nine/ On the New York transit line/ If the train jumps off the track, pick it up, pick it up, pick it up!"

Maybe some of these groups can pick up where their careers tapered off during their peaks. The Boot Camp Clik have a DVD and mixtape out now, Brand Nubian have a new LP scheduled for August and Black Sheep are due to put out another LP this fall.

For more sights and stories from concerts around the country, check out MTV News Tour Reports.