this happened a few months ago, went on my lunch break and a co worker said "have a nice lunch" i try saying thanks but all that came out was th th th tha tha than..... then i just went and took my break, didnt even eat my lunch because i was to embarrassed and angry at myself, i still cringe thinking about it, also whenever i come into work in the morning and people saying morning to me and i almost always stutter saying morning back, its rough.