A childhood belief about milk

My elder sister used to believe, when she was 5 or so, that white cows gave out white milk, brown cows gave out chocolate milk, pink cows gave out strawberry milk, etc., and that by eating the right coloured grass you would turn into a cow of that colour and start giving out milk. She used to eat grass covered in mud at primary school in an attempt to turn into a brown cow. Needless to say it never worked.