What's A Subtle Sign That Someone Really Isn't Intelligent?

We've all heard the phrase, they aren't the sharpest tool in the shed.

We'd never call someone unintelligent, but there are definitely signs that someone might not be the brightest in the room.

We want to hear about your experiences with people that made you think, "The lights are on, but nobody's home."

Maybe you know someone who lacks common sense; for example, they "forget" to wear sunscreen when they go to the beach.

Or perhaps your friend cannot engage in a conversation without raising their voice and insisting they are always correct.

Perhaps you know someone who believes everything they read on Facebook and refuses to fact-check anything.

Or maybe your family member acts rudely and inconsiderately towards others, disregarding their feelings.

We're curious to know your thoughts. Share your stories in the comments below, and your responses could be featured in a BuzzFeed Community post. Or, if you prefer anonymity, you can submit your story through this Google Form.