Surprise! B.o.B joined the Lawson boys to perform their recent joint single, 'Brokenhearted'. This image appears in the gallery:Lawson At The Summertime Ball 2013 - Pictures 8. Surprise! B.o.B joined the Lawson boys to perform their recent joint single, 'Brokenhearted'. Picture: PA 11 images See the full gallery: Lawson At The Summertime Ball 2013 - Pictures