I heard this on a morning drive-time show and looked it up. I seems swearing after an injury actually has a physiological affect on pain tolerance:
http://www.outsidethebeltway.com/swearing-helps-reduce-pain-study-says/ (http://www.outsidethebeltway.com/swearing-helps-reduce-pain-study-says/)
I turns out Mythbusters came to the same conclusion, but I guess I missed that episode.
Well, I could have told them all of that. I've been using this time-honored remedy for pain for many years.