Analysis of Oysters

Charming oysters I cry:
My masters, come buy,
So plump and so fresh,
So sweet is their flesh,
No Colchester oyster
Is sweeter and moister:
Your stomach they settle,
And rouse up your mettle:
They'll make you a dad
Of a lass or a lad;
And madam your wife
They'll please to the life;
Be she barren, be she old,
Be she slut, or be she scold,
Eat my oysters, and lie near her,
She'll be fruitful, never fear her.