What?s the best way for Jon Hamm to celebrate his Emmy victory? Nickelodeon has confirmed that Hamm will voice a character named Don Grouper in an episode of ?SpongeBob SquarePants? airing sometime next year. Grouper works for ad agency Grouper, Goby & Koi and, according to Nickelodeon, ?when Don?s in the room, everyone laps up his words like overpriced organic honey.? ?It?s a dream job in many ways and it doesn?t come without a cost.