The bawdier the better. NSFW and possibly offensive.

I once knew Dwarf named Mary,
Whose chin was beautifully hairy.
Her long golden tresses
Hung down to her breastes,
And inside them there lived a fairy.

There once was a Mermaid named Jo

Who was more useful up top than below.

Her naughty bits

Stopped at her tits,

So she could only suck off a beau.