Jenna Marbles has a hilarious video on this, where she basically tells you to make a weird face and hope it scares them away. (Here’s a link) I think The Face is brilliant if you’re not planning on meeting them ever again, but what if the annoying person you’re trying to avoid happens to be a teacher? Or a classmate? Or your boss? They’ll either think you’re insane and a) give you detention and/or send you to the school counselor b) avoid you like the plague and/or spread nasty rumors about you c) start a fight and/or hate you for life or d) fire you and send you to a mental institute. Basically, you might be better off just talking to them.
But this list gives you some suggestions that you can use that will help you avoid talking to the person without the person knowing that you’re trying to avoid talking to them. (And, for convenience’s sake, I will use ‘him’ and ‘he’ instead of ‘him/her’ and ‘he/she’ because typing so many of those is tiring and, um…annoying. I’m really not being sexist.)