What is "to be in one's cups"

Cup \Cup\ (k[u^]p), n. [AS. cuppe, LL. cuppa cup; cf. L. cupa tub, cask; cf. also Gr. ky`ph hut, Skr. k[=u]pa pit, hollow, OSlav. kupa cup. Cf. Coop, Cupola, Cowl a water vessel, and Cob, Coif, Cop.]

1. A small vessel, used commonly to drink from; as, a tin cup, a silver cup, a wine cup; especially, in modern times, the pottery or porcelain vessel, commonly with a handle, used with a saucer in drinking tea, coffee, and the like.

2. The contents of such a vessel; a cupful.

   Give me a cup of sack, boy.
   --Shak.

3. pl. Repeated potations; social or excessive indulgence in intoxicating drinks; revelry.

   Thence from cups to civil broils.
   --Milton.

4. That which is to be received or indured; that which is allotted to one; a portion.

   O my Father, if it be possible, let this cup pass from me.
   --Matt. xxvi. 39.

5. Anything shaped like a cup; as, the cup of an acorn, or of a flower.

   The cowslip's golden cup no more I see.
   --Shenstone.

6. (Med.) A cupping glass or other vessel or instrument used to produce the vacuum in cupping.

   Cup and ball, a familiar toy of children, having a cup on the top of a piece of wood to which, a ball is attached by a cord; the ball, being thrown up, is to be caught in the cup; bilboquet.
   --Milman.

   Cup and can, familiar companions.

   Dry cup, Wet cup (Med.), a cup used for dry or wet cupping. See under Cupping.

   To be in one's cups, to be drunk.