How do you spot immaturity?

I see it all the time, the most immature acts I see commonly done is petty insults directed at the person in question, bad mouthing people without them being present, using terms like "roast" and going "ooooohhhhh" when another petty insult is made towards someone they don't like, judging people by their appearance instead of their actions, showing no interest in getting to know someone before judging them, approaching political solutions based on what feels good, going out and partying instead of studying, repeating a point made by someone else in a silly tone, and simply laughing when their immature actions are criticized by someone who is growing up properly.
These actions show a very high amount of immaturity and convey that the person is almost certainly still in school, doesn't work, and is a Democrat. Not all democrats are immature, lazy, and ignorant, but almost everyone who is like that is a Democrat. What actions do you see from immature people?
How do you spot immaturity?
How do you spot immaturity?
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