There are, though, a lot of things to like about this comic:
-Most importantly, the punchline comes at the end. This is unusual for xkcd (see: the previous comic) and as you will notice, it makes the comic funnier.
-The punchline is conveyed in as few words as possible.
-Rather than tell you that this researcher is having sexytime troubles, he lets you figure out, at least a part of it, for yourself. Panel 3 interrupts the question (panel 2) and the answer (panel 5) making it a little more complicated.
Anyway, I still feel really gross about the comic - if it hadn't been for all those other do-me-without-a-condom style gross comics it might not be so bad, but as it is I can't help but not the subject. It's like Randall gets a certain amount of "explicit sex" credits and he's used them all up long ago on much worse comics.
But hey, let's try to be positive: Whatever you think of the joke, it was well executed, a rare trait for xkcd, and heck, even yesterday's comic was closer to being well executed than most. WHO KNOWS how great friday's comic will be?
update: I forgot all about this, but you should check out last Friday's first installment of Penny Arcade's Blamimations, made by Kris Straub and Scott Kurtz. I didn't really know what to expect, given that I don't read Mr. Kurtz's comic and I read the less-popular of Mr. Straub's comics (though I do enjoy it). I think it shows a lot of promise - the stories are the sort of absurdist looks at pop culture that I enjoy in Chainsawsuit, and the voices are done well, in a way that adds a lot to the humor (see especially the phone conversation at the beginning of animation #1). The big complaint I have is that the "animation" is too often just a still image - there's rarely any movement. It makes it harder to see as a movie and more just like a series of comics, with someone narrating the dialog. If that were changed (I would say the amount of animation needs to at least triple) I think this could turn out to be something quite excellent indeed. but enough about what I think. What do you think?