We love how playful he is!

Justin Bieber posted this pic to his Twitter account from the VMAs Sunday night. Maybe Brand and wife Perry were using 17-year-old Bieber to practice ... Perry Tweeted, "@Beyonce me & @rustyrockets are avail to baby sit anytime! We'z real responsible...ish :P."

Bieber Tweeted an extended "thank you" speech after winning Best Male Video. He said:

    "also thank u to my family, my friends, my team, and my FANS!! i got so much more to say now that it is over. haha. blanked out up there"