Andy Samberg plays the aforemention "Mellow Man," playing up his uber-laidbackness ("Hi, I'm laidback singer-songwriter Jack Johnson...Hackey sack..."), via a mock talk show called the "Mellow Show" in which mellow guests like Dave Matthews (played by Bill Hader) , John Mayer (played by Ashton Kutcher), and Ozzy Osbourne (Played by Dave Matthews) show up to discuss mellow things as soft-spokenly as possible.  Jack Johnson appears not to take too much offense to the gag, for he had Samberg appear in the video for "Are They Laughing at or with Me," in which they both get into this gnarly bar fight.  Totally not mellow.