I just don't "get" Invader Zim the way some people seem to, or anything by Johen Vasquez. Sure, I found a lot of the episodes to be funny, and there are a lot of memorable moments and characters ("These piggies are for science!"). It's just that the world that Vasquez creates is so aggressively unpleasant and deliberately disturbing that it's hard for me to genuinely enjoy any of it.
I remember a part of Vasquez's Squee! where the titular character's horrible parents begrudgingly stop to allow him to use the bathroom during a long road trip. Squee is then forced to finish his business as fast as he can so he can flee the grotesque roadside bathroom, chased out by the bloody diarrhea of a man who, though it is not explicitly shown, I could only assume is shitting out all of his internal organs while screaming in agony.
For me, that excerpt sums up Vasquez's work in a nutshell. If you can find something amusing or meaningful in it, more power to you, because I can find neither.