Just don't make a spectacle out of it. I haven't read other comments but I know some people seem to recommend to have a serious talk about it, say how you feel about it, why it happens. If you do that, you're giving the message that it's a big deal and he might end up treating you differently. That's the worst, when people see you in a different light. You don't want to be treated as a person that stutters, you are a person WITH a stutter. Don't let them pity you, it will annoy the living shit out of you. The more casual you are about it, the more "normal" you become!