ET was on the scene in the Big Apple Tuesday night as Beyonce hosted Gotham Magazine's gala, and the star gave us her candid review of her special "SNL" back-up dancer, Justin Timberlake -- in high heels and a leotard!

"He is so hilarious," Beyonce said of Justin. "We had the best time. It was so difficult to not laugh during the skit."

The sexy star also revealed she'll be at Barack Obama's inauguration -- and she'll be more than happy to sing for our next president if he wants her to!

Beyonce is the cover girl of Gotham mag's November issue. Don't miss her portrayal of music legend Etta James in 'Cadillac Records,' out Dec. 5.