I found that lyrics are unimportant. You can si g anything as long as you follow rhythm and intonation. However what's really interesting: there are definitely some actors or singers whos speaking or singing is very close to each other so that you can't be sure whether they speak or sing. And they do it very natural. So why is it so difficult for people who stutter to master this technique? Because thoughts are unorganized and you don't have time in live conversation to calculate rhythm and intonation? Maybe.