To look at. As a specimen of the ingenuity of certain
etymologists in tracing our language to Latin and Greek sources, may be
mentioned Mr. Casaubon's derivation of peep from the Greek opipteuo (to stare at).
or peep-bo. Hiding or skulking from creditors; in allusion
to the infant nursery game.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894