Amateur singers stutter when they forget the lyrics. Profession singers make shit up when they can’t remember the words. Ella Fitzgerald’s live performance of “Mack the Knife” showed her witty skill when she couldn’t remember the words. She pulled things out of her head like, “Oh what’s the next chorus to this song now / This is the one now I don’t know / But it was a swinging tune / And it’s a hit too / So we try to do Mack the Knife.” I know it is very hard for singers to remember every song correctly; therefore, learn to improvise as a backup plan isn’t so bad. You could turn your flaws into something novelty like Ella did in her Berlin’s concert.