Her pretty feet
Like snails did creep
A little out, and then,
As if they playèd at Bo-Peep,
Did soon draw in again.

Compare: "Her feet beneath her petticoat Like little mice stole in and out"—Suckling, Ballad upon a Wedding, st. 8. "And the prettiest foot! Oh, if a man could but fasten his eyes to her feet, as they steal in and out, and play at bo-peep under her petticoats!"—Congreve, Love for Love, act I, sc. i