Fine and dandy

Means first rate, splendid or excellent and is first attested in this sense from the late 19th/early 20th century. Before this, from the late 18th century, a dandy described a man with an obsessive preoccupation for dress and fashion, a fop. This usage derived from a shortening of an earlier expression ‘Jack-a-dandy’ which meant the same thing, but which dates from the early 1600s. The OED maintains that Jack-a-dandy derives from Jack being a common name for any man and dandy being a pet form of Andrew. Fine and dandy can be used to mean excellent or just the opposite when used with irony.