Sent to me by J^e, who always makes my day even when she's a coupla thousand kilometres away:

The Spangled Pandemonium by Palmer Brown

The spangled pandemonium
Is missing form the zoo.
He bent the bars the barest bit,
And slithered glibly through.

He crawled across the moated wall,
He climbed the mango tree,
And when the keeper scrambled up,
He nipped him in the knee.

To all of you a warning
Not to wander after dark,
Or if you must, make very sure
You stay out of the park.

For the spangled pandemonium
Is missing from the zoo,
And since he nipped his keeper,
He would just as soon nip you!