It often comes up in casual conversation that I study physics. Of course it would come up, since I'm devoting a significant part of my life to the subject. The common reaction is to express complete ignorance of all that complicated physics stuff. I must be so smart to be studying this stuff!
I'm not really convinced that you have to be super smart to study physics. But there I am, the representative of physicists, and I give off an air of intelligence. What can I say in the face of that kind of evidence?
I'm always amused when people bring up string theory. Well, of course you don't understand string theory! There are layers and layers of other physics you'd need to understand first. String theory is not basic physics! I think it's a wonder that string theory gets so much popular media attention when clearly the audience doesn't understand what's going on. You'd think that would make it uninteresting.
The other day, I was hanging out with a psychology student, making casual conversation with a few other people. I've decided that people say much sillier things to psychology students than to physics students. Some people decided that this was an appropriate time to advance their own grand hypothesis about psychology. How awkward is that? I'm trying to imagine a physics analogue: upon telling someone that I study physics, they say, "I have this theory that space is not continuous, but comes in tiny little pieces! What do you think?" Is there a way to say, "I think you don't understand your own proposition," without coming across as snarky?
And of course, someone at some point has to bring up Freud. My friend had to explain that psychologists haven't taken Freud seriously in a while. The person who brought up Freud said, "But wasn't Freud right that people are irrational?" Well, yeah... But it's not as if we didn't already know that. And Freud didn't have the right explanation for why people are irrational.
When skepticism comes up in casual conversation, people generally don't understand what you're talking about. The best reactions are when people just ask me to explain it. I explain that it's all about critical thinking, science, and the scientific method. But that's not clear enough, so I have to rattle off a list of things I disbelieve, like conspiracy theories, alternative medicine, psychics, creationism, and so forth.
I find that one of the best things to bring up are LaRouchians. Most UCLA students have seen the table set up on campus by the LaRouchePAC, but have no idea who they are. I just have to mention the picture of Obama with a Hitler moustache, and people's faces light up. "Oh, them! Who are they?" Let me tell you, they're crazy!
In general, talking about crazy people is a good way to gain sympathy for skepticism. Skepticism does not and should not only focus on the craziest fringes, but this is just casual conversation. I think it's fair to talk about the most amusing parts of skepticism.
Another common reaction to skepticism is to immediately jump to atheism and agnosticism. Either they take it for granted that skepticism and atheism are the same thing, or they act like the connection is a novel concept that they just came up with. It seems like people aren't aware that the relationship between atheism and skepticism is a longstanding topic in the community. I'm tempted to think of these people as newbies to the debate. But that's a horribly silly thing to be elitist about, so I listen people out anyways.