Let’s start by taking a look at the ending, the last four lines of No Exit:
INEZ: Once and for all. SO here we are, forever. [Laughs.]
ESTELLE: [With a peal of laughter] Forever. My God, how funny! Forever.
GARCIN: [Looks in the two women, and joins in the laughter] For ever, and ever, and ever. [They slump onto their respective sofas. A long silence. The laughter dies away and they gaze at each other.
GARCIN: Well well, let’s get on with it… (553-6)
Now you’ve got a few different things going on here. The first thing we’re going to cover is the laughter. Estelle, Inez, and Garcin have finally admitted that, indeed, they are doomed to an eternity of torment at each other’s hands. What’s so funny about that?
Nothing. This laughter has a lot less to do with things being funny as it does with things being absurd. The concept of absurdity plays a major role in Sartre’s brand of existentialism. He believes that Being – the human type of being, that is, being-for-itself (see Garcin’s "Character Analysis"), is in fact absurd. The absurdity of existence surfaces most when we face the fact that there isn’t a God. Without a God, there is no answer to our infinite series of "why" questions. We can either try to deal with this absurdity, or flee into bad faith, (see Garcin’s "Character Analysis" for more on bad faith). One example of living in bad faith is to turn to religion, and pretend there is a God when there really is not. And of course, the number one reaction to absurdity is laughter.
There’s a lot of absurdity in No Exit and, accordingly, quite a bit of laughter – not just at the end of the play, either. Take a look at these forerunners to that final passage:
GARCIN: I beg your pardon. Who do you suppose I am?
INEZ: You? Why, the torturer, of course.
GARCIN: [Looks startled, then bursts out laughing.] Well, that's a good one! Too comic for words. I the torturer! (68-70)
ESTELLE: Oh! Then we're to stay by ourselves, the three of us, this gentleman, this lady and myself. [She starts laughing.]
GARCIN [angrily]: There's nothing to laugh about.
ESTELLE [still laughing]: It's those sofas. They're so hideous. (97-9)
[Estelle presses the bell-push, but the bell does not ring. Inez and Garcin laugh.] (319)
While some of this laughter might seem sadistic, it’s more likely intended as recognition of the fundamental absurdity of their existence in hell. It’s fitting, then, that the ending of No Exit is steeped in this same sort of laughter.
OK, so what else do we have going on in that final passage? There’s the very last line to consider, delivered by Garcin: "let’s get on with it." What’s up with that? We’re thinking "it" = "the torture we’ve determined we’re inevitably going to inflict upon each other," but if you’ve got another theory we’re all ears. You’re also going to want to pay attention to that final stage direction: "they gaze at each other." Remember that hell is other people because the gaze of other people turns an individual into an object. It’s the look that constitutes torture, so it’s important that the play ends with Inez, Estelle, and Garcin all staring at (read: all torturing) one other. This is their hell and their doomed to remain here forever.