A person (usually a woman, though not always) who is given to exaggerated, disproportionate emotional reactions to relatively minor events or situations. Since I was an only child, my mother tended to be a bit of a drama queen about anything happening in my life. Ah, don't be such a drama queen, Tom, they're not going to fire you for a simple mistake like that.

To exaggerate or put too much focus on a minor issue and make it seem like a major one. You got one B and you're acting like you're failing the class. You're making a drama out of the whole thing, if you ask me. Let's not make a drama out of what's really just a minor setback.