What's the most tired you've ever been?

(In honor of it being a dreary Tuesday morning following a night where two sick kids repeatedly woke me up.)

Once, in architecture school, I stayed up 89 hours straight finishing a project. I momentarily passed out and almost fell on my professor while presenting it. After getting back to my apartment, I sat down on my couch at 5pm, and woke up at 11am the next day in bed, having fully changed clothes. I had no recollection of it.