I think my worst one was a line in Kieren Halpin's "Too long away" when I sang "Men with no suits and black faces". I met Kieren a couple of weeks later and mentioned it to him.... thinking it would make him smile.. He said its "men with black suit and no faces .. suit is singular .. its a state of mind not a state of dress". Anyway I felt suitably put in my place. He is not famous for his humour .. nice songs though.