Why does my pee have a red tint to it?

Visit your physician. It's impossible to say without more information. Talk to your doctor and don't try to self-diagnose. It may be as simple as medications or dehydration, but it could be something more serious that is causing blood or other abnormal products to be passed in the urine.
Blood (Maybe) A red tint to your urine may be from blood if you have a bladder infection (or other problem with your bladder or kidneys). Also it can be caused from muscles breaking down after strenuous exercise or trauma. If you have serious symptoms like fever, nausea, vomiting, abdominal/back pain you should see a doctor asap. Sometime a red tint to urine can be caused by food (beets) or drugs (azo/pyridum).
Possible blood. A number of things can cause urine to turn red. If you have an infection, the red color could be blood. Minor trauma after sex can cause urine to turn red. Menstruation (blood) can as well. Lastly, some medicines can turn urine different colors. If it persists, seek care.