Loud, cursing psychos. What do you do when you encounter them?

I was in a waiting room (family practice doctor's office) yesterday when a woman started yelling and cursing at a young couple with a small infant. It sounded like she was was accusing them of jumping ahead in line or something. (They were both waiting for a prescription.) After they left she kept on ranting; yelling and cursing "d@mn nosy b1ch needs to mind her own business". It was annoying and I really wanted to leave but I would have missed my appointment. It really caught me off guard. The staff didn't seem like they were doing anything to pacify her (or escort her out of the building). I mentioned the incident to a nurse and she just shook her head and muttered something about "d@mn crazy people". Besides the obvious (leaving, not making eye contact, and generally avoiding the person) what do you do in situations like this? Is there anyone out there who would (in all sincerity) confront the person and ask them to please shut the h3ll up? Would you do it if your (very young) kids were with you?