Joke's on you!

Prologue

Launchpad had been at mcduck manor since the triplets had started living there. He had been hired by their Great Uncle Scrooge as a limo driver, and eventually became their personal pilot for their adventures.
But with all their constant adventuring, everyone had gotten worn out.

One day, when the rain was pouring down and Louie was at his peak of laziness, Launchpad came into his room.
"Hey, Louie! Wanna play outside with this cool paper plane? Dewey made it for me."
Louie fake coughed, trying to sound sick. "Ah, s...sorry Launchp-pad. I'm suuuuper sick. But you c-can st-still go out there, I'm su-sure it'll still be f-f-fun."
"Well.. by myself?" Launchpad asked.
"Sure. It'll still be fun, trust me."
Launchpad perked up. "Alright then!"
Launchpad ran outside, throwing on his pilot goggles.
He ran down the street, chasing the paper airplane while it flew, still grinning. He kept running, running, and running until he slipped on the water with a thump, making his goggles fall off. He stood and steadied himself, seeing the plane lower and fall into a sewer drain. Great.
"NO!" Launchpad exclaimed fearfully. Dewey had made that just for him! It was special! It was... "My plane! Dewey's going to kill me!" He said, kneeling next to the sewer and peaking in to see if he could get it with his hand.
Suddenly, he saw a pair of eyes come forward inside the sewer, it's eyes shining with hunger in the light.
"Hey there, big guy.." a raspy voice called to Launchpad as he fell back, surprised. The, what seemed to be duck, let it's mouth be revealed, and it's eyes were hidden again.
"This is a pretty nice plane. You want it back?" It smiled, and had the mouth of a clown.
"Uh... Sure..." Launchpad said cautiously. "Hey, what are you doing in the sewers?"
"My whole circus! It was washed away by the storm... Now I'm stuck... It's so lonely down here..."
Launchpad looked sad. "Oh no, that's terrible! I can help you out!"
The creature smiled wider. "Really? You mean it?" It's teeth were huge and uneven, almost silly. It began to drool slowly.
"Sure! Here, give me your hand," Launchpad reached his hand out to help him, and the creature opened it's mouth, revealing a horrifying amount of sharp teeth, almost like a shark. He grabbed onto Launchpad's arm, and bit down on it. Launchpad pulled away, causing his arm to tear off, the skin from where his arms was attached at the shoulder turning red from the spewing blood.
"Help! Mr. Mc Dee! Dewey! Anyone! HELPPP!!!..." He was dragged into the sewer. And never seen again.

After Launchpad had been gone for a while, Dewey had started to get worried. With his short attention span, he should be back by now. The plane he made him wasn't THAT entertaining, was it? He decided to go find him and check on him.
After a bit of time, he found a pair of... Pilots goggles. His heart dropped to his stomach. He wouldn't leave these behind, right?
Then he froze, and his face went pale. He saw, in front of the sewer, a giant puddle of blood with little red feathers littered in it. "Launchpad?! Oh my God..." He sprinted back to the house, covering his mouth with streams of tears running down his face, so he could call the police.