It is where the lady's labia some-how sucks in the material covering it, therefore defining said labia and making it look like the hoof \ foot of a camel.
Kind of like 'hungry-bum' for the pussy ... I would have said 'fanny' but that's a term for the Uk
BTW ... there was very little camel-toe in the pictures .... Google 'camel toe' for more information :)