This is not necessarily what a toilet would sing, but it IS toilet related:

CHORUS:
We are circling the drain our whole lives through
We are going to snuff it, and there's nothing we can do
So live today and not be in a rush
For we'll all go swirly when the water's flushed

You can't choose what to hold onto, except sometimes there is ice
But mostly there is other stuff that isn't very nice
And if you're in blue water trying to stay afloat
You might find a tiny man in a little row boat
CHORUS

For some it is a challenge, for some they cannot swim
And some are seeking safety and they stick close to the rim
But as rising winds blow o'er us, in a mighty sphinctered shout,
There is just the drain before us, there can be no climbing out.
CHORUS

Some are floaters, some are sinkers, but one thing is true
All of us are stinkers when anal-i-sis is through
Some of us have money, some of us have fame
But when the universe digests us, we all come out the same
CHORUS

Oh, there is no other journey that will ever be the same,
No second chance horizon once you go down the drain.
When the welling whirlpool rises the stormy winds, they drive,
Give your heart a song, sing it loud and long, keep your dreams alive.
CHORUS