Guess Who This Cute Boy In His Blazer Turned Into!

Before this blonde dapper boy from Salt Lake City, Utah turned into a big Hollywood star, he was just throwing on his blazer and slacks, hitting the ballroom and having a dance off with his lil' sis.

Before he made a name for himself jiving in the ballroom and showin' off his moves, he spent his younger years studying and dancing in London. Yes, he can groove, but he's also written a New York Times Best Selling book.

The tables turned when he entered as a judge on "World of Dance" with Jennifer Lopez and Ne-Yo.