I've known many people who'd rather live life on the surface than ever find out who they really are.
Not sure what I mean? These are people who lead a superficial lifestyle (even within their intimate relationships with family and close friends) and only seem to be able to talk about how much better, cooler, or smarter they are than others or on certain topics -- think, the person who always has to be a "one upper" or a "know-it-all" in a conversation, or are quick to give bullshit explanations for their actions or behaviors when you know better.
So what can you do when you encounter or have to endure time with these individuals??
1) You see them for who they are and accept them as is. But in doing so, doesn't mean you have to agree with them.
2) You get to choose how much of your time, if any, you interact with this person. If keeping them at a distance feels good, then go with that.
3) If you cannot avoid interactions (maybe they're a relative or "in-law,") you can meet them where they're at by referring back to #1 and continuing to be YOU, just smarter!
And here's the important HOW:
When the opportunity arises, shift the conversation to other topics to diffuse their show-off behavior. That might mean you sincerely ask, for example, about their kids, a pet, or how their parents are doing. This transition may seem to catch them off guard a bit, but go with it and observe any changes. Did their demeanor relax more? If so, then those are the topics to stick to in future conversations.
But if their behavior doesn't change - their intensity level stays high or their tone of voice doesn't chill, then make a mental note of that and try to find a new safe topic. And if that still doesn't work, then don't waste your energy or time any longer trying to converse with this person and politely excuse yourself ASAP.
In doing so you are making the healthy (mental & emotional) choice to NOT participate in conversations that are shallow or superficial, and it frees the "show off/one upper" to find the people who enjoy these type of conversations with them more.