Just like the first two movies, the third film in the franchise also featured a host of celebrity cameos including the 18-year-old pop pop sensation, who played an extraterrestrial being.

"This will get me into trouble, but my theory behind Justin Bieber is that he's from Canada. Canadians used to sent spies to the United States. However, when those aliens tried to transmit the data back to their home planets, 3 percent of it got scrambled in the transmission so they got the wrong coordinates and ended up living in Canada instead.

"Canadians are 97 point something percent like Americans, except that they're way too nice and if you go into their homes, you'll go, 'Interesting! Fireplace in the bathroom. Therefore, the director said some Canadians are quite possibly aliens," Sonnenfeld said.

Sonnenfeld went on joking that Bieber was apparently not the only suspected alien in "MIB 3". "There was a Chinese seven-foot basketball player, Yao Ming, who is retired now. But how many Chinese people are over seven feet tall?," he added. The sci-fi movie has opened in theaters across the United States on May 25.