You can use air quotes to be sarcastic -- to show that you mean the opposite of or something different from what you are saying. These kinds of quotes are used in writing also. In all of the cases the person is being a bit unkind or showing displeasure at something. With all of Jim's "help" we'll never complete this project. (Jim doesn't help. He is either lazy and doesn't contribute or he makes a lot of mistakes, which causes us to have problems completing the project.) We're going over to the Smiths again for dinner on Friday. I can't wait to taste Mrs. Smiths' "cooking". (Mrs. Smith is a really bad cook. Her food is not tasty.) Jeff's news was so "urgent" that he had to interrupt the meeting. (Maybe he interrupted the meeting just to say he was going to lunch.) Linda to Fred: It was nice of you to help your "friend" Ellen get out of those wet clothes and spend the night at your house during the thunderstorm. (Fred and Ellen might be more than just friends.)

I agree both with Peachy and BRSwartz, They are both completely right. It is normally used with people who are close to you, I've hardly seen it in more formal situations. It is used show sarcasm or emphasize words. Here is a small example using script with a two guys named James and Kraig and a girl named Nicole. ~ Kraig: Hey, James, what are you doing with that gun?? Nichole: That "gun" is his science project. (She uses air quotes to emphasize that there is sucpision about he gun, and that perhaps said gunin't a gun at all.) James: Yeah it's a fake, it's actually a bubble blower. Kraig: Wow, really? Let me see! *presses the trigger and watches bubbles fly from it* Oh, you're a genius!! Nichole: Right... "genius" (Nichole uses air quotes again to imply sarcastially that she doesn't think that James is a genius) ~ Mostly we don't use air quotes we just add certain emphasis to words by how we say them. Like the saying "It's not what you say, it's how you say it." sorry to post this twice. I thought I had pressed the "Answer Question" button.

They are also used to mean "this is someone else's opinion, not mine". Of course this can lead straight into sarcasm, but sometimes they're used to indicate a different opinion or knowledge to yours. Eg. - Have you tried the new "twist top" wine bottles? (= that's what they call them) - Are you so worried about what "they" might say? (= I don't know who "they" are, it's outside my knowledge, but it's supposedly "significant"... OK, already dropping into sarcasm here, heh) Dr Evil demonstrates the giant "laser": http://www.youtube.com/watch?v=nw3dWOssOhs

I don't use them. I find that expression too informal and a bit silly. But that's just my personal point of view

To emphasize something or to express sarcasm. My teacher used them when explaining the lesson either to emphasize an idea or to express sarcasm.