Dialects and soaps

In Lancashire have heard someone called a ‘crate egg’ and a ‘soft apeth’, we also had relatives from Skipton but they never used the term ‘fat egg’.

I don't live in Yorkshire or anywhere near but "fat egg" does sound rather unlikely. As others suggest, perhaps it was "fat head"? The latter is a known expression across the UK, albeit not particularly common and rather out dated. It's the sort of thing you'd have seen in Billy Bunter I imagine.

I lived in Yorkshire for many years, but never heard fat egg, though I do wonder if fat head could sound like fat egg, with a dropped aitch, and a very soft d at the end?

Rural accents are the worst, but most 'urban' folk don't notice!

Doodledog

I don't watch Emmerdale, so can't help with 'fat egg'. Vera Duckworth in Corrie used to call Jack a 'crate egg', whatever that is, though. And as an aside, all of Gail Platt's children have different accents

crate egg probably means inferior. I imagine it refers to the imported eggs sold in the late 1950s that were considered inferior.

I’m a Yorkshire girl too and never heard it before.

Not a soap watcher but I’m sure anyone preparing for prison would be using a much more “colourful” repertoire.
Words I guess ITV cannot use pre the watershed!

Are you sure you didn’t mishear and they said fat head ?

I watch Emmerdale but can’t say I took enough notice of what they said I watched them fighting though

I was brought upon Yorkshire and Fat Egg is not a Yorkshire phrase? Fat head is.

I don't watch Emmerdale, so can't help with 'fat egg'. Vera Duckworth in Corrie used to call Jack a 'crate egg', whatever that is, though. And as an aside, all of Gail Platt's children have different accents

I’ve not heard the expression “fat egg” here in Yorkshire, but language continues to evolve, so perhaps this is now more of a thing.
I have heard of “good egg”, meaning someone is a good sort.