overdramatic
Showing way too much drama or emotion for a situation.
Overdramatic means reacting to something with way more emotion or theatricality than the situation calls for. When your friend acts like it's the end of the world because the cafeteria ran out of chocolate milk, that's being overdramatic. When someone throws their hands in the air and wails, “I'm ruined!” after getting one wrong answer on a homework assignment, they're overdramatic.
The word comes from combining over (meaning too much) with dramatic (meaning full of strong emotion or theatricality). Being overdramatic means you've cranked up the drama dial past what makes sense. A small disappointment becomes a tragedy. A minor inconvenience becomes a catastrophe.
Sometimes people are overdramatic on purpose to be funny or get attention. Other times they genuinely feel things intensely and can't help their big reactions. Either way, when someone is consistently overdramatic, others might start taking their complaints less seriously, like in the story of the boy who cried wolf. If everything is an emergency, nothing is.
You might say someone made an overdramatic exit by slamming the door after a minor disagreement, or that their overdramatic sigh could be heard across the room. The word suggests that while the feelings might be real, the expression of those feelings is exaggerated beyond what's reasonable.