A variation of the military and law enforcement term "ate up", which is a military term used to express someone's uselessness and inability to perform any task.
Also used to express a pointless or chaotic situation such as an unorganized task where nobody knows what they should be doing.
Finally, it is used to describe a hopeless situation.
example#1-Bob: "Hey, I heard Kevin could not score a 280 on the pistol course."
Fred: "Yeah- he's more 8 up than a soup sandwich".
example#2: Bob: "They want us to complete this assignment by next week, but no one knows who is supposed to be doing what"
Fred: "yeah, that's 8 up"
Example#3: Bob: "Dude, we are stuck in the middle of the desert, and I just ran out of water".
Fred: "yeah, this is 8 the fuck up"
From the WWII era meaning Section 8, a category of military discharge. Service members were deemed "Section 8" if they were mentally unfit for service. This included being found guilty for sexualal perversion. In modern times it is used to describe a soldier or piece of equipment that doesn't perform or present to military standard.
DS Slaughter- "PVT Snuffy, you failed to shoot at least one of the 40 targets with your rifle. Why are you so 8 up?"
PVT Snuffy- "Drill Seregent, I'm not 8 up, it's my rifle. It has been jamming and double feeding all day."
DS Slaughter- "You are still 8 up for failing to conduct proper maintenance of your weapon PVT! Your weapon will function properly of it is clean and lubricated!"