I could suggest you acting as if you're confident but even if it works I doubt it would work so long. What about getting rid of the fear that others would discover your stutter? Be open about it. If you need to introduce yourself and the block happens, just say "and as you can see, I stutter". It might seem odd to some people but it could be very beneficial for you, because this is how you empower yourself. You accept that thing that you're ashamed of and are open about it. Hiding things usually leads to them controlling our lives. If you can't not stutter at least minimize the fear of others discovering your stutter. Being open about it can reduce huge amount of stress that produces stuttering in the first place.