"just kidding", "no offense but..", and other indirect expressions of hostility are all forms of passive aggressive BEHAVIOR.
According to Wikipedia,
Passive-aggressive behavior is the indirect expression of hostility, such as through procrastination, sarcasm, stubbornness, sullenness, or deliberate or repeated failure to accomplish requested tasks for which one is (often explicitly) responsible.
We are all guilty of doing this. You say something sarcastic under your breath, an edgy expression of how you're really feeling just to follow it up with a cute little "just kidding", put on a mellow-dramatic show to display emotions which you will not own up to and even verbally deny... Passive aggression is a contagious and harmful attitude. At the root of this way of thinking and acting is one painful truth: we are not owning our emotions. To take responsibility for your emotions would mean saying what you mean and meaning what you say. It would mean that your actions and your words are in agreement, you wouldn't proclaim to feel one way then exhibit emotions that are obviously contrary. It would mean taking responsibility for our words: we wouldn't say we were going to do something if we have no intention to do so, I wouldn't act in a certain way to manipulate you, your actions or emotions. Passive aggression has become a silent weapon that is being yielded between co-workers, family members, friends, between everyone in our society. These actions, however 'mild' they may seem, are aggressive and harmful. By acting this way we are destroying the connections we have with others, and what's even more frightening (to me anyways) is the connection that we have with our own emotions.
An emotion is a very powerful thing. They are complex and persuade, sometimes even control, our mental and physical states of being and actions. No matter how analytic the person, at the root of everything, are emotions. So how incredibly scary, dangerous, and irresponsible is a rouge emotion. We are the only one that can take responsibility, much less control, of our own emotions. And for some reason taking control of emotions or even just seeing them for what they really are has gained a reputation for being scary. Your emotions should not scare you, your un-checked, out of control emotions.. yes, those may be scary. But our emotions are what make us who we are. They are our soul's response to the stimuli of existence. Without them we wouldn't be alive, they are what makes us 'alive'. So instead of running from them, explore - realize, analyze, and accept your emotions for what they are. Then try your best to express them in a healthy and positive way.