oh boy this used to happen to me alot and sometimes still does. i think that the self esteem gets crushed -more than it already is, so flip your thoughts (or yourself) on a dime and make funny of it cause everyone gets those moments apparently. put your "i feel so stupid" feeling aside and stop and look at them and admit (like your ok with having a brain fart...lol) and tell them that your embarressed and you say something like "oh sorry i thought i heard something else" you smile and then walk away as though it didn't phase you. and instead of appearing weak, according to them , they will notice that you're not worried about looking like a "fool" so it will make them comfortable to be around you. sort of like a pretend moment but you'll be amazed how will approach you next time then you can loosen up a little, some times when you put yourself out there and it doesn't seem to go so smoothly try mind over matter, don't be afraid of what they think cause those are alot of oppinions being thrown at you. what matters is yours' and make sure it's a positive one or at least try , it does get easier. lt's the beginning of assertivness aand along with that comes courage, strength and self esteem in yourself. it's worth a try but it worked for me. deep breaths, calm and collective. and you know what this gives you a chance to laugh at yourself and when it happens to them, you CAN say "i know what you mean" you'll relate and they'll see you as human.good luck and don't be ashamed of life's little brain fart's, if they don't get it them screw them it don't matter what THEY think,at least you get a chuckle at your expense.