Oh look, you can see what the effect of this is on a player. If you're a GM, try pulling it on your players some time.

It won't hurt if you also stroke a fluffy white cat while you run your game.

Transcript

{Kamino.}
Obi-Wan: That dinosaur cloning room was... odd.
Taun We: Here's Jango's room.
GM: Jango's young son Boba answers the door.
Boba Fett: Dad! Taun We's here with some stupid-looking guy!
Obi-Wan: Hello. My name is—
Jango Fett: Obi-Wan Kenobi.
Jango Fett: Well, well, well...
Obi-Wan: Sorry? Do I know you?
Jango Fett: I'm Jango Fett.
Jango Fett: The man who's going to kill you.
Obi-Wan: Uh... whu?
Jango Fett: But not just yet.
Obi-Wan: Well, that's a relief.
Jango Fett: First I'm going to kill everyone around you as you look on helplessly.
Jango Fett: I will take control of Naboo and make its people suffer.
Jango Fett: I'll bring down the Jedi Order you hold so dear, followed by the entire Republic.
Jango Fett: And then—only then—will I subject you to the most horrible tortures a being can endure.
Jango Fett: Before finally snuffing out your miserable little life.
Jango Fett: You're going to wish you'd never been born.
Obi-Wan: What did I ever do to you?
Taun We: I think you took his parking spot.