RALPH:  Hamlet repeatedly suggests, or orders, Ophelia, to retreat into a nunnery, or a convent.

SARAH:  Perhaps because of all the other rather lewd comments that Hamlet makes in this scene, his use of the word nunnery has sometimes been understood to be a reference to the opposite of a convent – that is, a brothel.

RALPH:  There are some jokes about prostitutes being nuns, and this sort of thing, from plays written around the same time as Hamlet – so this is possible.

SARAH:  But there’s also no reason to see the word this way in order to understand what Hamlet’s talking about.  Even if Shakespeare wasn’t making a vulgar joke, Hamlet is still almost obsessively concerned with Ophelia’s chastity here – it’s almost as if he were assuming that, unless she retreats to a convent, there’s simply no way for her to remain a virtuous woman.