Ha, this is so lame, but I don't care. :D
Warning: Some kinda lame hint at one-sided ZADR. ...Did I mention it's lame?
VOODOO
For the past five days, whenever Dib walked by Zim's base, he noticed that GIR was tied outside and giggling in a manner that didn't just seem to be a side-effect of his insanity. This was kind of suspicious.
Also for the past five days, Dib had fallen victim to an onslaught of unexplained cramps and backaches and other such various pains. This was highly suspicious.
And for the past five days, Zim had not let slip a single hint of any plans related to the takeover of planet Earth. This was the most suspicious thing of all.
The time had come for Dib to jump to conclusions, and because he was highly grumpy from lack of sleep, due to the continual muscle aches and whatnot, he decided to jump to the first conclusion that came to his mind, regardless of how stupid it was. What he came to wasn't entirely stupid – it made a perfect amount of sense to him, in fact – and he didn't exactly care whether he had proof or not. What mattered was that it made sense.
Clearly, Zim had done something to cause his pain, likely with the intent to kill him, or at least make him hurt a lot so he wouldn't feel up to any heroics.
So, right after school on the sixth day of his aches and pains, Dib headed over to the Irken's lair, all well and prepared to break in. And, as an afterthought, hopefully beat Zim up, as he'd probably have the element of surprise on his side. (As opposed to just a stitch in his side. Seriously, that thing had been bugging him for the past eight hours!)
When he kicked the door open, he found GIR on the couch, who squealed and waved energetically at him. Not really caring about the insane robot, Dib stormed over to the hidden elevator in the trash can, quite looking forward to giving the Irken a piece of his mind (and maybe a black eye, as an added bonus).
Before he could actually even open the trash can lid, of course, Zim took that moment to arrive on the main floor, contact-covered eyes widening in shock when he nearly collided with his enemy. Dib, however, hardly noticed the Irken's surprise, not even caring that it was quickly turning into anger. What he did care to notice was the little doll clasped in the alien's hand.
A little doll that looked frighteningly familiar.
Of course, given his typical bad luck, the moment he called attention to it, Zim positively freaked and demanded that the computer throw him out. Not fifteen seconds later, with much shrieking from Zim and howling laughter from GIR, Dib was flat on his face on the sidewalk, having been literally thrown out the door.
When beating on the base's door proved ineffectual, and banging on the window even more so, Dib grudgingly gave it up as a lost cause and resigned himself to a life of annoying aches and pains. At least, until he went home and discovered that Gaz had been stuffing rocks under his mattress over the past few days as some kind of petty vengeance for taking her snacks. It definitely explained a lot, though he wasn't sure why he hadn't caught on earlier, especially when she'd seemed so disturbingly accepting of his 'crime'.
Now all Dib had to wonder was exactly what Zim was doing with a doll that looked like him.
Because he's totally got the hots for you, Dib. (Either that, or he really is just trying to make a voodoo doll.)