Have you ever wondered if, behind closed doors, pop-cultural superstars ever engage in actual dance-offs, exposing their best moves until they come to, sweaty on the dance floor, holding a virgin vodka soda? Yeah, us either, but TMZ says this very event really happened last week, when teenage singing sensation Justin Bieber challenged box-office warrior Jaden Smith to a dance-off at Manhattan’s Lucky Strike Lanes, following their concert at Madison Square Garden. The challenge was set to Kevin Rudolf’s “You Make the Rain Fall†and was conveniently filmed for the upcoming Justin Bieber documentary. Sources say Bieber claimed victory after he busted out a moonwalk, and, in our heads, it looked exactly like the “Baby†video.