I will save you the obligatory lecture about how you know shouldn't be using anyway and if you feel like you need to fool others that you're not high you might have a problem. Oops.
Well anyway, what you would want is something that's sympathomimetic but doesn't actually have any side effects that are psychological or mood altering. I once heard of someone with your same dilemma acquiring ocular belladonna drops (still sometimes used to dilate pupils) for medical reasons and self administering a drop in each eye. I cannot attest if that works well or not, but I see no reason why it wouldn't; the theory behind it is good. Now: DO NOT just go out and buy /pick some Belladonna and get too lazy to make drops and just eat a leaf or berry. That would be terribly foolish. The whole plant is toxic. That's why you would have to buy from a reputable seller. Also, as always, titrate. You don't know how something will affect you, so start small, otherwise these people are going to think you switched to coke.
However clever the aforementioned is, I hope that the people you need to fool aren't your family. If they are, then suck it up for a while. It's one thing for your family to know you use; it's another to let them see you under the influence. The latter is disrespectful and you should avoid it at all costs, even if withdrawal is imminent. Whoever they are, they supposedly can tell when you have been using. You could just, NOT USE, if it's a short meeting.
Good luck man.
