Hate "dont take this so seriously" people

Imagine your group of friends has a game night, either video games or board games, and someone that is not a gamer joins in, but spends the whole time just trying to talk and doesn't bother trying to learn the rules or starts cheating and gets caught and someone calls on them and they answer "It's just ... you don't have to be so serious".

Or a roomate that "borrows" things and complains if you complain saying the same thing.

Or when you are in a line for groceries and someone tries to cut in saying they won't buy many items.

I don't if it's me, I feel like the common sense for a lot of people you can just be rude and inconsiderate as long it's for things they consider small.