How does one become nonchalantly hilarious?
1. Hang around with funny people and use their lines in new contexts. This technique has served me well for many years. When I was much younger, I was visiting my boyfriend's house and one of his roommates was a motorcycle gangster. I came down to the kitchen in the morning and put some bread in a very old, half-broken toaster. I asked the roommate, "Does it pop up by itself?"
He replied, "No, you have to stroke it first."
It was several months before I got the joke, but I use it all the time now whenever someone is trying to make something stand up.
2. In any situation, discard the first thing that pops into your head, because that's the expected statement. It's not usually funny. Get it out of the way, so the second thing can pop up (by itself). That's the unexpected statement. Unexpected = funny.
3. Language puns - word play - opportunities come up a lot. For example, in a conversation about Vaclav Havel, the former Czech president, my friend interjected, "Vaclav Havel? I love those Greek pastries.
OK, baklava only sounds vaguely like Vaclav Havel, but it cracked me up. Still does.
There's more, but I have to stop. It's getting late...