Antheia, to me it sounds like an attention grabbing thing..... is she bored? stimulated enough during the day? I know it would be hard with the 2 boys there as you have your hands full.... maybe she's saying all these strange things to get your attention? Has she been watching any TV that you aren't aware of? Sorry just trying to help!
Hopefully if it's just a 'phase' it passes.... you are concerned though and if I was you, I would probably talk to a health nurse about it and see what they think.... it would be upsetting hearing your DD say that