&%!!# helps when you're hurting
In 2009, British psychology researchers reported the results of a study that showed swearing altered pain perception. The study volunteers could hold a hand in ice-cold (41 degrees F) water about 40 seconds longer if they repeated a swear word of their choosing instead of a control word (one of five words they had picked for describing a table).
Swearing was also associated with an increase in heart rate, so the psychologists theorized that the body's fight-or-flight response is activated by the emotions that swearing produces. Pain perception takes a backseat once the body is in fight-or-flight mode.
In 2011, the researchers reported the results of a follow-up study. Swearing once again proved to be a pretty effective analgesic for pain from keeping a hand in cold water. But the cuss word was less effective for people who told the researchers they let expletives fly on a daily basis.