in your cups

in (one's) cups

Inebriated with alcohol. When you're in your cups, foolish ideas have a peculiar tendency of sounding like excellent ones. He called to apologize the following morning, claiming that he had been in his cups when he made those rude remarks.
See also: cup

in your cups

while drunk. informal
In your cups is now used mainly to mean ‘drunk’, but in former times the phrase could also mean ‘during a drinking bout’. Either could be intended in the passage in the Apocrypha regarding the strength of wine: ‘And when they are in their cups, they forget their love both to friends and brethren, and a little after draw out swords’ (1 Esdras 3:22).
1948 Vladimir Nabokov Letter I have received your letter… and can only excuse its contents by assuming that you were in your cups when you wrote it.
See also: cup