There are some typos or words missing, so I don't quite understand what was happening here. Are you saying your neighbor has a little 4 year daughter and she was playing with her feet? Sounds adorable to me, unless they're dirty people who don't bathe. It's probably not too sanitary if she was walking outside, but kids play in sandboxes, pick their noses and eat worms. They're kids!   If that kept you from eating breakfast, unless she was sucking on scabs oozing with pus, I think you have some issues you need to resolve. My next door neighbor has a 4 year old boy and one day I saw him peeing on the drain pipe from the gutter. They had company and he showed his friend how he could pee on the pipe. A 3 year old girl was watching them in wonder. They are just discovering all the wonderful things they can do with their little bodies. After reading your post, I tried to suck my big toe, but I can't stretch that far. Wish I had someone else to do it for me, but that's a whole other subject. Chill out and try sucking on a toe. It might change your attitude. :-)

I work with children ages 2-13 on a daily basis, Daycare, This is totally normal behaviour.
This age group has a thought process that is all their own, maybe their toe was burning or hurt, who knows, but compared to some of the things I have seen children do this one is perfectly fine.
In my 27 years of providing childcare, I have seen most everything, I still occasionally am surprised by something but this would be rare for me . Miss Bee