What could usually indicate that somebody is hiding something from you or scared to confess something?

Anonymous
I don’t mean hiding something by hiding a physical thing, but hiding something in terms of something they did to you behind your back and shouldn’t have, and are thinking of telling you. But are scared to confess or tell you directly?
Updates
+1 y
Oh okay and if it’s not randomly? But it’s the subject of our conversation at that moment? Like they never ask outside of that or at random times, only when we’re specifically talking about that or the subject is specifically about things people would do that would make me leave them and they just ask out of curiosity kind of like “oh even if it’s because of that or not done out of intent?” Etc
What could usually indicate that somebody is hiding something from you or scared to confess something?
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