Rock is a confectionery made and sold in many of the UK's seaside holiday resorts. As the character Ida says in Graham Greene's novel Brighton Rock[?], "It's like those sticks of rock: bite it all the way down, you'll still read Brighton."
... so that they flapped as the wearer walks, the term was already doccumented as in use in the United Kingdom as early as 1912.
Writers and artists in the United ...