pencil-eater

A concept, idea, project, etc. that is so confusing, it leads the habitual pencil biter to skip biting the unfortunate number two, and go straight to eating it.

"Hey, y'know this question's a real pencil-eater, it's been stumping me for weeks!"

"This project's such a pencil-eater, you mean to tell me I need how many sources for it? I can't even find one! Who wrote this textbook anyway?!"

"Man, adobe choosing to trick its customers into a year long subscription sure is a real pencil-eater! It's like they wanted a lawsuit or something!"