The LORD has mingled within her a spirit of confusion, and they will make Egypt stagger in all its deeds, as a drunken man staggers in his vomit.
Drunken people aren't notorious for pulling together great feats of walking in the first place.
They are known for upchucking their night's "fun" however.
Combine the two and you've got a recipe for disaster: slippery, vomit-laden, unstable disaster.
Nice metaphor Isaiah.
We get the picture.
Egypt will stumble about and is a danger to themselves and others.
Egypt is on the floor covered in vomit, passed out after several unsuccessful efforts to lift themselves out of their own puke.
What could inspire less confidence than a drunken person walking in slippery sewage?