<the worse verse thread seems to have petered out (at least momentarily :)>

Gallantly swallowing the momentarily (I'm sure I can get used to this if I try....), let's get back to wrose verse. I used to know someting that ended up

...then Peter's ?? will pall
and Paul's will peter out.

Can anyone give me the complete version?

And where does 'peter out' come from anyway?