Josh Groban.Photo: Patrick McMullan

At the Mandela Day Concert at Radio City Music Hall on Saturday, we thought it would be fun to ask singers to come up with some lyrics to honor Nelson Mandela's 91st birthday. "This is going to be a really terrible rhyme," crooner Josh Groban warned us before giving it his best shot: "Nelson Mandela for many more years we hope you’ll stay, I hope you can feel the love and support we show you on this special day." View our Party Lines slideshow to see if anyone else had better freestyle skills.