My coworker asked me to proofread his report.

This joke tickles our funny bone through a delightful blend of hyperbole and relatable absurdity. When a coworker asks for a proofread, the implied task is to fix a few typos or grammatical slips. The punchline, however, takes a dramatic left turn, suggesting the original report was so riddled with errors that the "proofreader" essentially had to start from scratch. It's an exaggerated, over-the-top reaction that perfectly captures the exasperation many of us have felt when confronted with truly terrible writing.

The humor also stems from a very common office experience. Anyone who has ever worked in a collaborative environment has likely encountered a document that was, shall we say, a "work in progress" that leaned heavily on the "progress" part. Proofreading, editing, and reviewing others' work are staples of many jobs, and the frustration of sifting through a mess of mistakes is universally understood. The joke taps into that shared pain, turning a tedious task into a moment of comedic exasperation.

Ultimately, the joke is funny because it takes a mundane, everyday scenario and pushes it to an illogical, yet perfectly understandable, extreme. It's a comedic nod to the silent battles fought by editors and diligent coworkers everywhere, transforming a groan-worthy task into a laugh-out-loud moment of shared professional woe.