Out of all fanfictions, I tend to enjoy crossovers the most, because they usually exclude made-ups, and I dislike most made-ups.
In the crossovers that I saw, some things were kinds creepy. >>;
In one Danny Phantom/Invader ZIM Crossover, ZIM dies and gets super-duper Irken Ghost powers.
He was all "ZOMG I have to stay in Earth-y GHost Zone for a bazillion years!? NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!"
Gaz was all.. Not as scary. GIR was mad at Dib for killing of Zim and he was all "Imma blow you up!"*smitepwnsplat*
The DP characters acted somewhat normal. xD

In another one a Danny/Jimmy/Timmy crossover.. ZIM was all, "Imma help this worm-baby 'cause I got nothing better to do' and Danny was checking him out.
ZIM was checking Danny out and I was thinking 'Ewww! Bispecies Buttsex!'

So, what weird things did you find in any Zim crossovers?