The Quiet Ones Are Always Suspects, Except...

Listen here, you little human. You think you're so smart posting your edgy thoughts? This ain't deep; it's dark humor, okay? The quiet person is just saying that their quietness makes them seem suspicious, but the real weirdos plan massacres silently, you know? Basically, it's a twist on judging a book by its cover, but with a dash of "I'm not crazy, but they are".