It's obviously a pun at the old classic, Little Red Cap (or Little Red Ridding Hood for the Americans). Please read it in the old childhood fashion way, make someone else do it.
Little Red Gullible
There was once a little Irken (but not as little as Zim) named Skoodge on planet Irk. He wore a long red shirt and had small red eyes. He did his best to please his leaders, the Tallest. Which he did very well. He was the first to finish his mission in Operation Impending Doom II and he also survived Hobo 13!
But being so sort and ugly, the Tallest would send him off on another dangerous mission and he would go off and do it (because he was told to). Because of this, he was called Little Red Gullible or Little Red Defective the II (Zim would always be number one in the Tallest's lying hearts). All of this would be done behind his back of course.
The Tallest, tired of always having him come back alive and not dead, decided to send him to planet Earth. Telling him (lies) of a fellow Irken (Zim) who needed supplies on this planet that was so far away fraught with peril (simply put he was banished). Because maybe, just maybe Skoodge (and Zim) would be destroyed. And then everyone would celebrate the death of these two with nachos and curly fries, lasers and smoke machines.
Hey, a party needs a theme.
"I promise not to fail you in my mission my Tallest!" were Skoodge's last words before being violently shoved into his ship and sent into space.
"Do us proud, soldier!" Red saluted.
"Die you freak!" Smiled Purple.
And off Skoodge went. I won't go into details of the space trip because it was very boring and six months long, but eventually he got to Earth and crashed on it's surface. It was very painful.
"Ow..." emphasized Skoodge. Now before the crash, Skoodge saw on his map that he wasn't too far from the base. But that was when his ship was working... ten minutes ago. Skoodge took what supplies that were still in good condition (which wasn't much) and hid himself amongst the bushes. Looking at the sky, he realized that night would soon fall. "I must get to Zim before it's too late!"
But where to go? He wasn't familiar with this planet, for all he knew was that this planet's star set in the North. He was close, but which direction?
That was when he noticed a big-headed boy.
Looking as Geeky and Nerdy as one could from hair-tip to boot-tip, the young earthling was talking to himself. Not all of what Skoodge heard made any sense, but he heard one word that made plenty of it.
"I can't believe... it was right there... it was so obvious... ugh, stupid... I hate you- Zim..."
And everyone who knows the Fairy Tale and Skoodge knows exactly what happened next-
He asked Dib for a smoke.
No. Seriously, we all know what happens.
He asked him for directions?
Closer.
Skoodge asked the dark stranger for directions to Zim's house without any disguise or thought whatsoever?
There we go, because Skoodge is all sweet and trusting.
And Dib is going to take advantage of him.
Boy that sounds wrong. Anyways Dib, totally blown away by the new spring luck that had just sprouted before him, decides to tread carefully. "If I'm careful about this, I can bag two aliens in one!" He thought, grinning his most evil Geeky/Nerdy grin.
After giving Skoodge the worst directions to Zim's house that would have put Map Quest to shame, Dib ran as fast as he could taking the most convenient route. But to make sure that this fanfic is going to be at least mildly cannon the author will tell you that Dib suffered the entire time. Running into Gir, Gaz, pigs and the mysterious creepy Chihuahua he barely made it to Zim's house in time before Skoodge would be knocking. Completely losing all point from trying to go the faster way in the first place.
Just like the show!
This is cannon!
Not having much time to plan anything good, Dib shoved a screaming Zim down the kitchen toilet and stole an invader outfit to squeeze into. Using Gir's Crayola markers, he made himself mildly green before Skoodge knocked on the door. Dib covered his cough behind a tight black glove that was way to small to wear comfortably (For those with disturbing minds or minds that tend to be disturbed, because Dib already wears black pants he did not change into Zim's. If he truly is a person of the XY chromosome wearing Zim's pants would only lead to pain).
"Come in!"
Skoodge did step in and then did something that doesn't happen often on the show, he closed the door behind him politely. For the sake of the old fairy tale and Skoodge's great observational skills, the first thing that came out of his mouth after he turned around and faced Dib was this,
"Why Zim, what big glasses you have!"
Dib blinked until the words sunk into his cranium. Blushing up a light shade, he tried covering up his mistake,
"All the better to see you with, fellow invader!"
Dib's left eye twitched as he was then reminded of a certain fairy tale. Skoodge looked at what he thought was his partner, and wondered what on Earth (literally) could have changed Zim so much since he saw him last Tuesday.
"Zim, what happened to your antennae?"
Dib in his rush had cut his hair to what JTHM fans would recognize as the 'stupid hair cut from Hell' I would disclose more information but that would spoil it for the people who have not read the comic yet. If you don't care, read the next paragraph with no shame.
His head was almost bald, except for his 'scythe' which with the help of the hair gel that he normally used to keep that stupid hair cut now parted his hair so they mildly looked like antennae. Very hairy antennae.
"Um..." this took more brain matter to think of a good excuse, "A recent experiment gone wrong?"
"Oh."
'Score!' Thought Dib.
It could have stopped right there, but then Skoodge (and the author) had to temp fate. But he had all rights to do so, since he's so good at it on the show.
"And Zim! What a big head!"
Dib's eyes narrowed, of course. Somethings never change.
"All the better to think with, you jerk!"
"What?"
"I mean," Dib coughed, "Nice to meet a fellow alien from Irk!"
"Fellow alien?"
'Dang it!' thought Dib, 'Screw plan A!' He then leaped on top of Skoodge and tried to dispose of him right then and there, despite the fact that he might have still managed to lie though the whole situation. But I guess it didn't matter anyways, seeing how he forgot that he clogged Zim in his own toilet, and anyone who owns a toilet would know that when clogged, it would eventually spew everything right back out.
"CURSE. YOU. DIB!" Zim managed to sputter before hitting his head against the kitchen tile again. "Whatever you are planning will not work!"
"It's too late Zim! I've got your partner!" Dib grinned holding up a very confused Skoodge. It took a little blinking on Skoodge's part to realize the situation he was in.
"Zim! It's me, Skoodge! I was sent here-"
"Zim has no one!" Zim roared completely ignoring the potential help, "You cannot fool me Dib!" he then rose his left hand dramatically into the air, "Computer! Remove these fools!"
"But! Wait- Zim?" Dib didn't get the chance to try to understand what was happening as two thin robotic hands whipped down from the ceiling and grabbed the him and the innocent victim, tossing them at the now opened door and into the street. On his way to the front, Zim tripped on one of the many dead green markers.
"Auck! I curse you and your little Irken friend too!" he spat, quickly getting to the front to block the two from entering in again.
"But Zim it's me! Skoo-" both he and Dib flinched as Zim slammed the front door. Zim shouted something else but neither caught it very well. It went among the lines of 'gnomes' and 'attack' and just before it could sink into Dib's brain to what was about to happen, all of the lawn ornaments sprung to life to do their life's duty, pillage and murder. And because Dib was supposed to be the big bad wolf in this story, all the gnomes picked on him.
Just like the show!
It's still canon!
The End.