Not earth-shattering, but an odd enough rhyme that I find it interesting that I';ve come across two instances by very different artists.
The second instance is from "Weid Al" Yankovic's "Wanna B Ur Lovr:"
You're absolutely perfect
Don't speak now, you might spoil it.
You're eyes are even bluer
Than the water in my toilet
The first instance, as all will recall, is from Ian Dury & the Kilburns' "You're More Than Fair:"
A tender moment,
Don't let nothing spoil it.
I shall caress your clitoris
As we reach the toilet.
I'll note that the above video is of an Ian Dury tribute band performing the song. Every video I could find of Ian Dury performing this, or of a studio version contains a (slightly cleaned-up version with the clitoral reference replaced by something slightly less risque. But I still have the original 45 with the lewd version.