To His Coy Mistress is probably the best known example. Donne uses the metaphysical conceit of the flea mingling the blood of the lovers. If there's no shame in the flea combining their blood in its body, then how can there be any shame in two people making love? Even when the young woman kills the flea, the poet has the last word - of course!
Mark but this flea, and mark in this,
How little that which thou deniest me is;
It suck'd me first, and now sucks thee,
And in this flea our two bloods mingled be.
Thou know'st that this cannot be said
A sin, nor shame, nor loss of maidenhead;
Yet this enjoys before it woo,
And pamper'd swells with one blood made of two;
And this, alas! is more than we would do.
O stay, three lives in one flea spare,
Where we almost, yea, more than married are.
This flea is you and I, and this
Our marriage bed, and marriage temple is.
Though parents grudge, and you, we're met,
And cloister'd in these living walls of jet.
Though use make you apt to kill me,
Let not to that self-murder added be,
And sacrilege, three sins in killing three.
Cruel and sudden, hast thou since
Purpled thy nail in blood of innocence?
Wherein could this flea guilty be,
Except in that drop which it suck'd from thee?
Yet thou triumph'st, and say'st that thou
Find'st not thyself nor me the weaker now.
'Tis true ; then learn how false fears be;
Just so much honour, when thou yield'st to me,
Will waste, as this flea's death took life from thee.