Thanks Mike for your really valuable advice. I intend to try this out, whether or not it ends up being the way I go with this song. For now, I changed the last line of the second last verse (the one with the boy who drowned) and the whole of the last verse to something that I think is lyrically much better. The result is that it stays closer to the rest of the song and doesn't dissolve into the same kind of chaotic silliness. I won't repeat the whole lyric here, just the last two verses that changed.

How much is that doggie in the window?
How many puppies are at the pound?
How much do they pay Kim Kardashian?
Did you lose this quarter I found?

Tell me who... in a firing squad
Wouldn't shoot to miss.
Tell me who... when a heart is breaking
Would refuse a kiss.

The revised version is here:
https://soundcloud.com/gavin-sinclair-5/pretty-smart-sister-2/s-IwBvt