No need to feel bad about it, says a 2-year-old study from the journal NeuroReport that's been making the rounds this week. Swearing actually helps reduce the pain you feel.
Researchers from Keele University in Staffordshire, England, asked test subjects to put their hands in icy cold water, and see how long they could stand to keep them immersed. (This is a common practice to test pain, because it leaves no mark and does no physiological harm.)
They then had the study participants either say a swear word or a neutral word. They found that those who invoked foul language were able to withstand the pain better than those who kept it clean.
The researchers think that swearing induces a flight-or-fight response, and thus, "nullifies the link between fear of pain and pain perception."
This doesn't mean you should let loose indiscriminately, though. The effect worked best for people who did not swear often.