DANDY. That’s the dandy; i.e. the ton, the clever thing: an expression of similar import to “That’s the barber.”

DANDY GREY RUSSET. A dirty brown. His coat’s dandy grey ruffet, the colour of the Devil’s nutting bag.

DANDY PRAT. An insignificant or trifling fellow.

Quoted from: A Classical Dictionary of the Vulgar Tongue. London: 1796.