Some of the best English literature has employed the device. For instance, Chaucer wrote The Canterbury Tales using rhymed couplets:
Whan that Aprill, with his shoures soote
The droghte of March hath perced to the roote
And bathed every veyne in swich licour,
Of which vertu engendred is the flour; . . .
Shakespeare often used heroic couplets (rhymed couplets written in iambic pentameter) when writing poems for use within his plays. Here's an example from A Midsummer Night's Dream. Helena and Hermia speak using rhymed couplets in Act I scene i of the play. Here's a bit of Helena's scene-closing soliloquy:
Love looks not with the eyes, but with the mind;
And therefore is wing'd Cupid painted blind:
Nor hath Love's mind of any judgement taste;
Wings and no eyes figure unheedy haste:
And therefore is Love said to be a child,
Because in choice he is so oft beguiled.
Alexander Pope ("'Tis hard to say, if greater want of skill/ Appear in writing or in judging ill") often employed them; so did John Dryden ("All human things are subject to decay,/ And, when Fate summons, monarchs must obey"). So, too, did William Blake ("Tyger, Tyger, burning bright/ in the watchfires of the night"). And Ogden Nash ("In the world of mules,/ there are no rules.") And Dr. Seuss ("I do not like green eggs and ham./ I do not like them, Sam I am.") And Jack Prelutsky. And lots of other children's poets.
Today's icon is directly related to an excellent display of rhymed couplet skills, coming as it does from the movie The Princess Bride, of which I am excessively fond. Here's what the script for the scene between Fezzik the giant and Inigo Montoya looks like on the page:
Inigo has gone close to FEZZIK, who is very distressed at the insults he's just received. As Inigo casts off.
That Vizzini, he can fuss.
(a slight emphasis on the last word)
(looking at Inigo)
... fuss ... fuss ...
(Suddenly, he's got it again,
emphasis on the last word.)
I think he likes to scream at us.
Probably he means no harm.
He's really very short on charm.
Oh, you've a great gift for rhyme.
Yes, some of the time.
(he starts to smile)
(whirling on them)
Enough of that.
As they sail off, we hear their voices as the boat recedes.
Fezzik, are there rocks ahead?
If there are, we'll all be dead.
No more rhymes now, I mean it.
Anybody want a peanut?*
*Technically, this is slant rhyme - it almost rhymes (just as, later in the movie, the Man in Black/Westley is "mostly dead"). Just as "[t]here's a big difference between mostly dead and all dead," there's a big difference between an exact rhyme and a slant rhyme (which almost rhymes). But that is a topic for a different day. In this case, it's used for comic effect.
TO SUM UP: If you're setting out to write a rhyming couplet, remember the rules: Two lines. That rhyme. (Metre optional, but usually a good idea.)