In Act Three, scene i, the first of the two times that Margaret appears in Richard III, by William Shakespeare, Queen Margaret is furious and vengeful.
Margaret is the widow of Henry VI (...who was murdered by Richard in Henry VI, Part Three)...Onstage, she becomes a choric [acting as a chorus] figure: offering her opinion on the play's action, and prophesying doom and misery on Richard and his supporters.
In this part of the play (lines 220-230), Margaret is confronting Richard ("Gloucester; Richard, Duke of Gloucester; afterwards, King Richard III of England"***) and cursing him and those who follow him for the murder of her husband (in Henry VI, Part Three) and her son.
This section is spoken directly to Richard as she curses him:
Thy friends suspect for traitors while thou liv’st,
And take deep traitors for thy dearest friends.
In these lines, Margaret hopes that Richard will suspect his friends as traitors, and accept traitors as his best friends.
No sleep close up that deadly eye of thine,
Unless it be while some tormenting dream
Affrights thee with a hell of ugly devils.
Here, she curses him with the inability to sleep, unless his sleep is filled with horrible dreams that frighten him with images of hell's devils.
Thou elvish-marked, abortive, rooting hog,
Thou that wast sealed in thy nativity
The slave of nature and the son of hell.
In these lines, Margaret insults Richard. "Elf" is of German origin—elves were thought to be "dwarfish and malicious."* So saying that he is "elvish-marked" is insulting his behavior and his stature: she's describing him as nasty, evil and ugly. Then she calls him an " abortive** rooting hog," which simply describes him as an "imperfectly developed" hog—sniffing and snorting through muck and garbage for something to eat. "Sealed in thy nativity the slave of nature and the son of hell" means that he was born with a disposition enslaved to that of an uncivilized animal of nature, a demon or devil.
Thou slander of thy heavy mother’s womb.
Thou loathèd issue of thy father’s loins.
Thou rag of honour, thou detested—
These last lines are also insults. Margaret tells Richard that he is an embarrassment to his mother's womb, and the hated offspring of his father's siring. She ends by telling Richard that he is a piece of garbage: a rag...without honor. She is ready to continue with "thou detested—" but Richard interrupts her.
(And one has the satisfaction of hearing Margaret tell Queen Elizabeth that one day she will wish she had aligned herself with Margaret to also curse Richard, referring to him as: "this poisonous bunch-back'd toad—", line 246.)
When translating Shakespeare, remember to look up words you don't know, and don't be afraid to change the order of the words in his sentences. Don't stop at the end of a line unless there is end punctuation (period, etc.). A comma asks you to pause, but without punctuation, you need to move on to the next line to gather an understanding of the entire thought. (Sometimes Shakespeare is following a rhyme scheme, and the words may be in an order that provides a rhyme of one word with a word at the end of the sentence, two lines previous.)
*Additional sources: http://www.etymonline.com/index.php?term=elf