Source : Webster's Revised Unabridged Dictionary (1913)

Flip \Flip\, n. [Cf. Prov. E. flip nimble, flippant, also, a
   slight blow. Cf. {Flippant}.]
   A mixture of beer, spirit, etc., stirred and heated by a hot
   iron.

   {Flip dog}, an iron used, when heated, to warm flip.