Seasoned roleplayers simply don't show any fear when confronted with giant monsters and other dangerous things that should cause any real person to quake in their boots. As a game master, it can be difficult to generate a suitable atmosphere of tension during situations like this.
But then some player can make an innocent out-of-context comment that will cause everyone to react in genuine alarm. Yeah. We're not prepared to go quite that far with Jar Jar.
Obi-Wan: We set off through the centre of the planet.
Jar Jar: Ooh, mesa make sure mesa go to the toilet first!
GM: You guide the bongo through deep, dark underwater caves.
GM: Suddenly... you feel a shudder! A giant fish is trying to eat the ship!
Qui-Gon: Is it a tuna?
Obi-Wan: I gun the propeller, hoping to rip its mouth to shreds.
GM: Uh... the propeller isn't powerful enough.
Qui-Gon: We fire the rear weapons!
GM: There are no rear weapons.
Qui-Gon: Turn around and fire the main weapons!
GM: Actually... there are no weapons at all.
Jar Jar: Theesa big fishes eats bongos alla time!
Obi-Wan: I use my Force Suggestion. "Go Away!"
GM: You can't, you're just a Padawan.
Obi-Wan: ... "Padawan"?
Qui-Gon: A woven rug.
GM: A Padawan is a Jedi apprentice. You're training under Qui-Gon's supervision.
Jar Jar: Can mesa be a Jedi too?