They said "Bye, Bye, Bye" in 2005, but a source tells the new issue of Us Weekly (out Friday) that 'N Sync recently reunited in Orlando.

Justin Timberlake, 30, joined former bandmates Lance Bass, 32, Joey Fatone, 34, and JC Chasez, 35, to celebrate Chris Kirkpatrick's 40th birthday at his Florida home. "Chris was surprised!" a source tells Us.

For more on the boy band's surprise reunion, check out this week's Hot Stuff video, as explained by Us' Senior Editor Ian Drew and special guest Eli Lieb.

Also in the roundup: Prince Harry behaves like an American commoner, new details on Nicole Scherzinger's split with racer Lewis Hamilton, Chloe Grace Moretz bonds with Dianna Agron, and much more!