Flavor Flav Was the Life of the Party at Annual Star-Studded Holiday Bash

Flavor Flav is getting the holiday season started.

On Saturday the rapper, 64, headed to producer Jennifer Klein's annual holiday party with several friends — including close pal Prophet (who accompanied him to Variety's Hitmakers event earlier in the day) — for a rollicking night out.

The star, dressed in a festive red jacket, pants and a matching clock necklace, spent the night on the dance floor showing off his moves and singing along to hits, including ABBA's "Dancing Queen" and Britney Spears' "I'm a Slave 4 U," spun by Tendaji Lathan.

At one point, Prophet offered his hand to a partygoer and helped her down the stairs in the backyard of Klein's home, an onlooker tells PEOPLE.

Several couples also made it a date night, including Camila Mendes and boyfriend Rudy Mancuso, Katie Lowes and husband Adam Shapiro, and newlyweds Joey King and Steven Piet, who mingled on the patio later in the evening with friends.

Former That '70s Show stars Wilmer Valderrama and Topher Grace also reunited at the shindig (where Don Julio specialty cocktails, Fiji Water, Baskin Robbins ice cream treats and A Golden State were passed), holding court at a table.

Leslie Mann hung out with a few girlfriends and made it a family night with her daughters Iris and Maude Apatow.

Closing out the party was Zachary Levi, who picked up a Tocaya burrito and was in high spirits throughout the night, dancing and singing with friends.

Others in attendance, including Vanessa Bayer, Garcelle Beauvais, Heather Graham, Logan Lerman, Bill Maher, Sebastian Maniscalco (who picked out pieces of chocolate from a Reese's buffet), Thomas Middleditch, Chord Overstreet, Cobie Smulders and more, sipped on Justin's Sauvignon Blanc and mini bottles of Piper-Heidsieck Champagne as they snacked on Nothing Bundt Cakes, Crumbl cookies and Baked by Melissa cupcakes.

On their way out, guests — who picked out Cosabella pajamas and Nest New York candles — stopped by a Baileys treat cart for hot chocolate, Dunkin' donuts and Shake Shack burgers.