Have you noticed how some people are far more serious when conversing with just one person, but act like goofballs if a third person -- a friend, maybe -- is also involved in the banter? The reason for this is simple: We feel more vulnerable when we're alone. If a close friend happens to interject, though, we seem more at ease. All of the sudden, we feel comfortable enough to crack a joke or two and know that at least your friend will appreciate and likely laugh at it. I see this happen all the time in the workplace. For example, when around one or two of her "office buddies," my co-worker Jenna loves to bust my chops about my being too quiet in the office. But if it's just her and I, she acts like a completely different person -- a lot more sober and humorless. If none of Jenna's closest co-workers are around to hear her jokes, those she isn't as chummy with may not find them funny at all, so she'll likely refrain from telling them. So what's ...