The bladder is located above the muscles in the bottom of your pelvis. Sometimes the muscles get a little bit flabby when you have a baby or as you age, making it harder to stop yourself from peeing.
If you have to run from the room when someone tells a joke, there is hope. Many doctors recommend Kegel exercises to help you stop peeing when you laugh. Squeezing the muscles in your pelvis to firm them up can help prevent the problem. Also, you should drink less caffeine and use the bathroom more frequently, because the bladder leaks more when it's full. Try to empty your bladder if you're going into a social situation. Don't let people tickle you!