I just remembered the one I hate the most! When some older person who hasn't played a video game since the Atari 2600 comes up to me playing DS and says "Are you winning?"
It drives me insane because games aren't like that. In a single player experience, there aren't many cases where you can simply say "I'm winning". Usually I just say "yes" and that makes them drop the subject, but it still drives me up the wall when people ask that.
Also, when I'm writing something down for a blog post, article or video script, and some moron comes up to me and asks "are you writing a story?". There are other things one can write on a piece of paper you know. >:/
I also hate it when I'm playing a game, and someone comes up and asks "what'cha playing?" usually followed by "can I play?" First off, it's none of your business what I'm playing, and I sure as hell don't want you watching over my shoulder and getting your bad breath of unidentifiable origin in my face. Second, no you may not play my game because you don't know what you're doing and will kill me and make me lose my progress.
Then there are the people who ask "what'cha drawing?" usually followed by "can I see?" No you may not look at my drawings you big snoop. Maybe some people don't WANT to show off their drawings! Maybe some people just like to doodle random crap that doesn't really need to be shown off. Or maybe some people aren't particularity great artists, and are self-conscious about it. DID YOU EVER THINK OF THAT?!
And finally, when you ask someone "Do you know where my *insert object* is?" and they reply "Where did you have it last?" If I knew the answer to that I wouldn't be looking for it you goddamn idiot. >:/