Katy Perry has released the hilarious, nerd-tastic video for the fun summer jam Last Friday Night (T.G.I.F.) and it's a doozy. Really funny with some fum cameos by Darren Criss, Kenny G, Kevin McHale, Debbie Gibson,Hanson, Corey Feldman and, of course, Ms. Friday herself Rebecca Black. Good for you Katy. You are NOT vain. Ha. Oh, the guy with the abs is my new obsession.