Felix Delbruck wrote:

>'Bona nox, you silly ox; bona notte, dear Lotte (i.e. Charlotte); bonne nuit
>- fie, fie! Good night, good night, we've got a long journey ahead of us,
>gute Nacht, gute Nacht, it's high time (that we were asleep); good night,
>sleep tight and stay fat and healthy!'

I think what made some of the catch and round lyrics a little risque was
the juxtaposition of certain syllables with others.

Mimi