petticoat tail
/ˈpɛtɪkəʊt ˌteɪl/Scottish
noun
A triangular piece of shortcake or shortbread biscuit, cut out of a round and scalloped at the outer edge. Usually in plural.
Origin
Early 19th century; earliest use found in Walter Scott (1771–1832), poet and novelist. From petticoat + tail, apparently so called on account of the resemblance in appearance.