"Mad Men" star Jon Hamm joined Beck on stage at an after party for his Madison Square Garden show, where he sang the Cars 1978 hit, "Just What I Needed,"
Jon Hamm & Beck Perform Together at Secret Bar Show in NYC – Superstar Guest List Revealed! Jon Hamm and Beck are this NYFW s biggest surprise show! The 52-year-old Mad Men alum and the 53-year-old rocker paired up for a secret performance at Mulberry…