'A tale for winter' or 'a winter's tale' was a common phrase referring to a trivial story or silly pastime for children. Notably, Shakespeare's title is "The Winter's Tale" (as opposed to "A Winter's Tale), a cheeky play on the common phrase staking out this play as the ultimate form of the trivial pastime and a celebration of the same childhood delight in stories and storytelling we see in Mamillius.