Model, Charlotte Kemp Muhl and boyfriend, Sean Lennon, are the music artists behind the band, The Ghost of a Saber Tooth Tiger. Can you believe that Sean is the son of John and Yoko Lennon? As a couple, Charlotte and Sean naturally make the modern day John and Yoko. Although I'm not a fan of their music, this couple's band name blows my mind. The Ghost of a Saber Tooth Tiger. If you don't think that's cool, than I probably don't know what cool is.