It's not great, but I'm making it up as I type, so.....

The Dursleys

If you were an orphan,
And you needed a place to stay.
Don't go to the Dursley's;
I think you'd rather run away.

It could get annoying,
That Petunia's way too clean;
Dudley is a rude, fat pig,
And Vernon's very mean!


Well, there you go!