>> reporter: of course this. [ screaming ] we heard the screams before. for the monkeys. ♪ hey, hey we're the monkeys and people say we monkey around ♪ >> reporter: new kids on the block. ♪ the right stuff >> reporter: and the '90s boy band gods, nsync. ♪ tearing up my heart when i'm with you ♪ ♪ you don't know you're beautiful that's what makes you beautiful ♪ >> reporter: now, one direction. like the boy bands before them, the product of an off-stage musical mastermind. in their case, simon cowell. >> i just said, why don't we put these five in to a group and it literally took ten minutes. >> reporter: who do you see that is your favorite?