M.J.
Hi J.,
I have been in a situation like this in the past and I have said something. It seems to help if you use humor or make more of a light hearted comment.
We were in line at the zoo and when the women got off the phone I told her "Man, it's a good thing my kids did not hear that because they would have charged you like $50 for all the F-bombs!" She was a little shocked that I said something and then laughed it off and said that rates have gone up since she was a kid and then said she was sorry.
I would not suggest repremanding an adult in public or out right tellng him that he has bad behavior. It was a public place and he does have every right to use any kind of language that he wants to. Even though it's totally tacky and inconsiderate.