To be in your cups

[sugaredone]

I gather that this means you are drunk, but can anyone explain this phrase more fully to me?

[xyzzyplugh]

well, 'they drank from cups, not glasses. As in reading, 'to be in your books' so in drinking, 'to be in your cups' : maybe.

[Quizmonster]

'Cups', in the plural. has meant 'drunken revelry' since the start of the 15th century, presumably - as xyz says - because that's what people drank from in those days. The very first use of the phrase using 'in' appeared in a 1611 version of the Bible, in the apocryphal book of Esdras Chapter 3 verse 22, which reads: "And when they are in their cups, they forget their love both to friends and brethren, and a little after draw out swords."

[JohnPPotts]

I'd always assumed this meant you had passed out drunk, so your head was lying on the table amongst the empty cups or glasses - though this may be completely wrong!