In English folklore a Johnny Noddy is the dancing light reflected from a mirror or reflective object such as a watch face. A Johnny Noddy could also be the light you see reflected in a cup of tea.
"I have not seen her. But through the embrasure I often saw the sunlight flashing and leaping like a thing of life, and I knew it was what the children call a 'Johnny Noddy.' Now a 'Johnny Noddy' argueth a mirror, and a mirror argueth a woman, and frequent use thereof argueth a beautiful woman."
References
Johnny Noddy Wikipedia(Text) CC BY-SA