i have friend that is bad breath, how can i say to him?

Simple, if your a true friend to him and really concerned about what he is you can tell to him in a nice way, that you really cared for him and you don't want other's make laughed at him. That's why true friends are there to protect and tell the truth even sometimes hurt. But that's the role of being a true friend. Maybe it is much hurt for him if someone will tell him and not his friend, it is a insult to him that you his true friend not tell the truth that he has a bad breath.

If he really is your friend, he wouldn't mind you telling him something that will help him. I have a cousin who has the same problem as your friend has. I really tell him that his breath stinks and he should try to brush his teeth. He is offended but I explain to him that it's for his own good. After a while he doesn't feel offended.