Joffrey is an idiot, let me tell you how
It's the end of the world, and what are they doing?
Standing here waiting for Joffrey to finish poking the undead thing they literally stumbled upon (well, she literally stumbled upon; she has the entrails on the bottom of her skirt to prove it).
And how the hell do you get THAT sort of stain out? Not that her appearance really matters anymore; all they do now is walk from village to castle/hall/ruins to another village looking for food and actual people and try not to get eaten.
It's only the four of them now so that makes things a bit easier, less of a "hey full course buffet here!" signal every time they arrive at a new place.
Of course, she's the only sane one left of this bunch.
All Cersei does is drink from the seemingly endless flagon of wine she carries around and makes snide remarks at her. The remarks are actually better though, than having to hear her bemoan the fact that Jamie is gone and why does no one but her care?
(Jamie is not really gone, he just ended up being one of a thousand or so undead staggering around; the only exception is he's the only one that has a gold hand, so they can see him coming from a mile away. For whatever reason, he continues to follow them and likes to try to take a bite out of any of them that lags behind).
The Hound is really the only one she can stand; he doesn't talk, except to grunt things at her ("there's a zombie behind you") and he's the one that keeps them mostly safe (the only time she sees him smile is when he's joyfully hacking away at whomever is in their way/trying to eat them again).
Joffrey is still an idiot who refuses to acknowledge the actual danger they are continually in. Point in fact, that he's still currently poking the thing, with his own finger no less. He's not even smart enough to prod at it with his sword or a stick or something other than his finger!
He's laughing at it now, because the thing is just the top half of a torso trying to pull itself around with its hands.
The laughter stops when it latches on to his finger and bites it off.
Now he's screaming like a little girl and they're running along after him. Of course, now she's the one that gets to laugh.