I'd guess the scenario is more like a social setting where you know some of the people and don't know others. And you're having a "what do you do?" kind of conversation where you respond with "computer stuff" and then the person you're talking to, or someone in earshot, says something like "Oh, maybe you could help me with mine...".

That's happened to me several times. I've also had people do a similar thing in work settings--people who weren't even direct coworkers.