Once, two rats were talking.
'Try this, ' said the first.
'It is of xanthous essence with bewildering taste
Humans call it swiss cheese.'
'That's fascinating, ' said the second rat.
'I've got a florid essence of my own called,
sharp cheddar.'

They decided to trade,
But each was worried losing his favorite flavor.
Each surreptitiously took a mouthful of
What they have in hand, first.
Then each blurted the same.
'There's no difference.'
They agreed, it wasn't
A fair trial.