Let's get one thing out of the way: whatever this little moment was, it was certainly about a "rape." I wish this went without saying, but of course if you click on some of the links in this post you will find people (usually male people) in comments sections saying hey, butt out, this is what happens in long-term marriages all the time! I didn't realize it was such a turn-on to have sex with people who are literally unconscious but apparently some people are into that. In any event, sad to say, like many rapists who don't think they are rapists because they are really very nice people and pay their taxes and have never lurked in dark alleyways in major urban areas, the salient question in any analysis of whether rape has occurred is whether or not your partner has consented to sex. Unconscious people can't consent because they are unconscious. Tautological, I know, but there you have it. So, hence, rape.
As for the other half of the claim that this is a "joke": I'm not really clear on what it was meant to convey, given that Liz's sense of disgust is internal to it, and yet it hardly seemed like a condemnation of Pete. No one uses the word "rape." Pete is acting sort of irrationally the whole episode. The repetition of the image of Pete's wife hitting the headboard is especially puzzling, like it was meant to rub our noses in something. I wish I knew what.
Rape hasn't traditionally been a big subject of commentary on 30 Rock, at least as far as I recall. I haven't time to review every episode right now to support that statement, though. Perhaps I've become somewhat numb to mentions of it. I'm ashamed to confess that until Melissa McEwan pointed it out at Shakesville, I hadn't noticed the scene was actually just one of three rape jokes the 30 Rock premiere contained, the other two being more or less casual dismissals of child rape.
In the end, the joke felt more like an attempt to get a rise out of the audience than anything else. Like the 30 Rock writers are saying to us: "We'll go anywhere in search of a good joke." Unfortunately, they were led down the garden path this time, it seems, because the only people who seem to be laughing are a bunch of jerkish blog commenters.
Rape jokes are a polarizing subject. Some people say you should never make them, and my personal sympathies do tend to lie with that camp. The standard objection to that line of thinking is that comedy often has a strong relationship with sacred cows, that usually it's the "un-PC" nature of the subject that gets people laughing. But my problem is not with the subject, it's with the execution. As in this case, it's too easy to screw up the joke, and it leaves you looking like an asshole who trivializes rape. Which I'd imagine isn't all that attractive a prospect for most people, and possibly least among them someone like Tina Fey, who's made her career out of a new brand of smart-funny-lady-writing that, whatever dissonances it contains, at least seems to aspire to intelligence.
The thing is, as Fey probably knows, good, smart, incisive humor isn't just about making people uncomfortable—it points outside the discomfort to some larger concept worth reconsidering, or thinking about. In order to do that effectively, you have to presume that the social context of your joke is reasonably coherent, that people know when a rape is a rape. Unfortunately, that is not the case; apparently there is significant disagreement, socially, on this point! Apparently some people read a joke about rape as a joke about "marriage," which elision is, you know, incredibly screwed up, but there you have it. Maybe when we live in a world where we can rely, consistently, that people know that, jokes about rape will be as smart as they are effective. Until then, I'd suggest we all resist the temptation.