According to Scientific American, swearing might actually help with pain:

How swearing achieves its physical effects is unclear, but the researchers speculate that brain circuitry linked to emotion is involved. Earlier studies have shown that unlike normal language, which relies on the outer few millimeters in the left hemisphere of the brain, expletives hinge on evolutionarily ancient structures buried deep inside the right half.

Next time you slam your thumb with a hammer, you can keep that in mind while you cut loose :)