Butterfly and Crocodile

At swimming once,
I went to turn from front to back
and just kept turning,
just kept turning,
turning over,
over and over,
till the swimming teacher said,
'What are you doing?'
and I said, 'I'm a crocodile.
This is the death roll

that crocodiles do
to tear their prey apart.'

'OK', she said,
'You need to work on your butterfly now – though I must say
your crocodile
is really coming on.'

From Bookside Down.