So what the heck is being slimed anyway? My definition of being slimed, not a very technical word but you get the drift, is when you let someone else's bad energy, words, mood, attitude, or behavior totally take over your disposition and ruin your moment, your day, even your life. More clinically I think this would fall into the category of intrapersonal and interpersonal boundaries and how they intersect.
Why does this happen to us and why so fast? I believe it is a flight or fight thing. It happens when we perceive threat. I think it is because we all have internal values and boundaries from our upbringing and culture. When those values get crossed we go into protection mode. I have a strong internal value around being polite. I was taught to say please and thank you growing up. As well, I was encouraged to share. When I think someone has crossed what I perceive as appropriate, I react. I perceive rudeness and take that energy on internally. But, I have choices.
So, what can I, we, and you do about it? Well, first be aware that it happens. We sometimes let other people affect us and in some not so good ways. Second, we can also work hard to not assume the other is trying to threaten us or do us "wrong." There is no way to know what is going on with others unless we ask and they tell us. Most behaviors have an explanation. Most people have a story. Other things we can do are to talk to a buddy who understands us (I did this), or forgive the offending person for offending and yourself for reacting. Finally, we can remember, being human, we've probably slimed someone else without being aware of it.
However, if this is a chronic reactive state, you may want to look at yourself and reflect on what is making you be so reactive. Are you overworked, stressed, or feeling generally unsupported in life? Ask yourself, "Who am I and what does this reaction say about me right now?"
And importantly, if another person repeatedly acts in concrete ways that you perceive as disrespectful, you may have to decide whether or not talking to that person about the problem is warranted. Talking it out takes courage, but you'd be surprised at how healing it can be.