http://pagingdrgupta.blogs.cnn.com/2009 ... hat-hurts/
He mentions a recent study which claims that swearing has an analgesic effect; it actually helps to increase pain tolerance.
For the study, Stephens asked the participants to submerge one hand in nearly freezing water for as long as they could while repeating a curse word. Later the participants submerged the same hand again, this time repeating a word they would use to describe a table. When people were cursing, they kept their hand in the water for 40 more seconds than they could otherwise.