I dunno guys. I really dont give a shit what people wanna call what I do. It's like anything, people are quite ignorant about specific things that you do. It's in ones nature to generalize. Without generalization, really, could we have any sort of, conceptual understanding of anything? I believe that to some extent, we stereotype and organize things the way we want, in order to relate some personal meaning to our surroundings. With music I always get this 'OMG CAN YOU PLAY THAT SONG FROM THE PIANIST"...It gets a bit old, but they're in essence opening themselves to a conversation about something that you love.
But here's the thing guys. I believe it's our responsibility to educate those who make such broad sweeping generalization as to be totally off the mark. I mean we all do jiu jitsu, we all love it, why therefore should we not promote it? I usually just say I'm going to class as well, and that's just fine, but if people ask 'oh what kind of class?' I tell them what it is that i'm doing. Sometimes I'll get a bruce lee impression, but if you settle them down, they're almost always quite interested in what you have to say. I have a few people from work interested in joining BJJ because of it.
People usually will not take the time to understand something that they dont understand by themselves unless it affects them. Having someone they know doing something is a perfect example for how it could affect them. That's WHY people are saying "oh, my son does karate." Is it their fault for not going out of the way to understand your passion, which until this point, has had no place in their lives whatsoever? No, it's just obliviousness, not stupidity.
Getting frustrated about it is just elitism in my opinion, and a bit self-important.
Just my two cents.