1) When you get so paralytic that you're constantly throwing up, unable to function normally.

2) When a journey takes much longer than usual. Most common reason due to drinking too much and having to stop every 10 minutes.
Wow look at that guy, he looks proper sheep'd

Alternative use-
That journey was so sheep'd, took us like 2 hours longer than usual!
by cheesetoastie July 9, 2019
Get the Sheep'd mug.