Certain people use this expression to be hurtful and condescending, while others enjoy being recognized as extraordinary.
We are window lickers.
Alternatives are 'spaz' or 'mongole'.
Mother: You shouldn't be unkind, they are people too
Small child: Eugh! Look at that one windowlicker with the snotty nose!
Mother: Tee hee! They are funny aren't they!