I see that the song is credited to "Paul Anka, Jacques Revaux, Claude Francois", so presumably the man responsible for "I ate it up and spit it out" and so forth is" is Paul Anka.

It occurs to me that the word of the original song in French are likely to be significantly better. Maybe somebody would like to find them and post them. It'd provide an alternative way of dealing with this kind of situation to be able to offer to sing it in French.