This term is used to describe someone who is very soft. You would use the term to describe an athlete who milks an injury that most people would just shrug off. Take for example a hockey player who lays on the ice like he just got hit by a freight train,when he only got a good check.
Hockey player 1: Why is mike laying out on the ice? He hardly got hit.
Hockey player 2: He's sunbathing butter!
Hockey player 2: He's sunbathing butter!
by TV CAR March 8, 2010