There are some people with whom you can improv; there are others who don't have the ear, or the sense of humor, for such a thing. Comedienne Tina Fey has said that improv means saying "yes" to everything that comes your way. On an improv-comedy show like Whose Line Is It, Anyway?, this is exactly what the actors must do, creating whole universes simply by affirming each other's whimsy. If you've decided you're on Mars, building an igloo, your partner might try speaking like an Inuit and asking you whether you want seal for dinner. Your partner might also decide that that funny light in the Martian sky is an alien ship landing in your vicinity, which means you need to stop building your igloo and go exploring. Little children are often great with these sorts of flights of fancy; adults, being self-conscious, overly dignified, and overly ossified, often fail to retain the necessary mental and emotional flexibility to do improv well. Tina Fey writes:
The first rule of improvisation is AGREE. Always agree and SAY YES. When you’re improvising, this means you are required to agree with whatever your partner has created. So if we’re improvising and I say, "Freeze! I have a gun," and you say, "That's not a gun. It's your finger. You're pointing your finger at me," our improvised scene has ground to a halt. But if I say, "Freeze, I have a gun!" and you say, "The gun I gave you for Christmas?! You bastard!" then we have started a scene because we have AGREED that my finger is in fact a Christmas gun. Now obviously, in real life, you're not always going to agree with everything everyone says. But the Rule of Agreement reminds you to "respect what your partner has created" and to at least start from an open-minded place. Start with a YES and see where that takes you.
A lot of people don't get this, which is why some of them fail to connect with me when I try to be funny. One of my coworkers, for example, can be Spock-like in his literalism. He has a Japanese-American girlfriend from Maine, and there's another coworker in our office who hails from Maine. When we hired another employee who is also from Maine, I joked to my coworker, "Aha—a karmic connection!" Spock blinked and asked, "What do you mean?" I said, "Your girlfriend's from Maine, right?" With a look of utter seriousness, Spock said, "Yeah, but our other coworker's from Maine, too." By this point, a person open to improv humor would have said something like, "Yes! This was destined to be! All roads lead to Maine!" Instead, the humor fell flat, and I apologized for the bad joke.
Having an improv frame of mind means being open to new things and saying yes to life. It's not a bad way to live, and it will certainly improve your sense of humor, thus making you less of an asshole. Try it. You'll feel better about yourself and the world.