So it turns out that an old supervisor of mine, Richard Stephens, won this year's Ignobel Peace Prize for his research on how swearing lessens the individual's sensation of pain.
Here's a link to a PDF copy of the study; for those without the inclination (or, should that link be deleted, the ability) to read the full study, Stephens et al.'s design was relatively simple.
They began by asking their participants to give a list of words that the participant would use if their thumb was struck by a hammer, and then a list of words that they would use in describing a table. Each participant was then subjected to two variants of a cold pressor test - one in which they were instructed to repeat the first swear word on their 'hammer' list whilst their hand was submerged, and one in which they were instructed to repeat the corresponding word on the 'table' list (given that the participants were students, it's not terribly surprising that only one of sixty-seven participants failed to claim that they would utter a swear word in the event of a hammer striking their thumb). The order that each participant experienced these conditions was randomised, and prior to each trial the participants held their hand in a container filled with room-temperature water for three minutes.
The results went against their initial hypothesis; swearing increased pain tolerance (the amount of time participants held their hand in the icy water), and reduced the reported sensations of pain. Their suggestion in the final paragraphs of the paper is that swearing might increase levels of aggression, which in turn might induce hypoalgesia (a reduced sensitivity to pain).
It's certainly a nice piece of research, although I'm wondering if the effect size might have differed had alternative methods of causing pain been used. That suggestion comes from a few papers I've read that found evidence that redheads have a lower tolerance for thermal pain (e.g., the ice used by Stephens et al.), yet a higher tolerance for pain caused by electric shock. It's very, very tenuous, but suggests to my mind that we shouldn't hastily assert that all forms of pain are of the same kind - or, at least, experienced in the same way.
Regardless, it's good to see the work get such public recognition.