Out of curiosity, when do you use this in Scotland? My grandparents use it in Cornwall but only about very pregnant women!!
Ok, that's what it literally means, but what is the idiomatic translation?
I think, drunk.
In my Australian childhood, we would say "full as a gugg " , usually when someone was drunk. (gugg being an egg) Now we say "full as a tick"
Wiktionary gives it as "full to the brim"