I've just been laughed at (with) by a work colleague who was passing in the corridor.
Laughed at. For no reason.
Admitedly myself and this person have had a number of nonsensical exchanges before. She speaks at me, and for some reason I can't understand a word she says. I don't think I've ever resolved a single one of her sentences - there's something blocking me from making language out of her words.
Its not an accent thing. As far as I can tell, she's got uses standard English pronunciation, with no detectable regional inflection.
I must presume that everything she has ever heard me say has been equally mystifying. Or perhaps her brain assembles my own seemingly-random string of words into something approximating an Eddie Izzard set. So we've ended up just pulling funny "friendly" faces at each other and grunting.
If I wasn't such a sensible chap it'd be easy to get paranoid. But ever since I wandered into a chip shop having forgotten that I'd got the "c-word" written on my forehead in biro, funny looks get me wondering what's on my face...