Used (mainly) to describe the state of drug users after a few too many lines/pills/tabs/hits or combination thereof. Once a person's lower jaw takes on a mind of it's own, seeking only to meet with their eyebrows and beyond, they're Guernsey. That being said, Guernsey is so much more than a word for gurning
It may also used to describe when something goes badly wrong and variations of this word are perfectly acceptable. For example, please feel free to add an -ing to make a handy verb for any occasion.
Guernsey is also one of the Channel Islands, which is just fine by us.
1. I took so many E's last night, can't remember much but I got really Guernsey.
2. The aircraft pilot came in too steep for landing and for a minute things were all Guernsey.
3. That ice-cream man is really Guernseying my ice-cream, he should be fired.