
Allow me to explain. My interpretation (as John Donne) in square brackets.
The Flea
Marke but this flea, and marke in this,
How little that which thou deny’st me is;
Me it suck’d first, and now sucks thee,
And in this flea our two bloods mingled bee;
Confesse it, this cannot be said
A sinne, or shame, or losse of maidenhead,
[Look, this flea took a bite out of me, and you too. So actually me coming inside you is no different to this flea having both of our bloods inside its belly, see? Let's shag asap because it won't tarnish your reputation in any way (apart from being compared to a dirty, micro insect, that is].
Yet this enjoyes before it wooe,
And pamper’d swells with one blood made of two,
And this, alas, is more than wee would doe.
[Actually, this flea conceit is far filthier than me shagging you because it involves blood and I won't hurt you *that* much]
Oh stay, three lives in one flea spare,
When we almost, nay more than maryed are.
This flea is you and I, and this
Our marriage bed, and marriage temple is;
Though parents grudge, and you, w’are met,
And cloysterd in these living walls of Jet.
[are you getting the flea conceit yet? Once again, imagine we are the bloods in this flea. There are 3 bloods, mine, yours and the flea's. That's one more blood fusion than me and you merely getting it on]
Though use make thee apt to kill me,
Let not to this, selfe murder added bee,
And sacrilege, three sinnes in killing three.
[since this flea has bitten us both, we're as good as married, but I'll settle for a shag for now]
Cruell and sodaine, has thou since
Purpled thy naile, in blood of innocence?
In what could this flea guilty bee,
Except in that drop which it suckt from thee?
Yet thou triumph’st, and saist that thou
Find’st not thyself, nor mee the weaker now;
[Getting it yet? We're no better than this flea. God, this is as hard work as trying to explain a rhetorical question to Katie Price]
‘Tis true, then learne how false, feares bee;
Just so much honor, when thou yeeld’st to mee,
Will wast, as this flea’s death tooke life from thee.
[Killing the flea was easy - well, yielding to me will be just as easy and painless. Promise]