Justin Timberlake admits it: He's a "mama's boy."

"We're best friends," the 'N Sync singer says in the January issue of YM magazine.

"I've done some stupid things, but there wasn't anything that I couldn't talk to my mom about. She told me, 'You're gonna do dumb things and you're gonna do great things. As long as you learn from them, that's all that matters.' "

Timberlake turns 21 on Jan. 31, and has a list of things he'd like to do before then. They include getting his girlfriend, Britney Spears, to be the first to say the words "I'm sorry."

"She is one of the most hardheaded people I know . . . in a good way," he said. "It's funny how when you're with someone the things that you find attractive are also the things that drive you up the wall."