TO TAKE AN OATH, verb. phr. (common).To drink; TO LIQUOR UP (q.v.).MATSELL (1859).
HIGHGATE OATH, subs. phr. (old).A jocose asseveration which travellers towards London were required to take at a certain tavern at Highgate. They were obliged to swear that they would not prefer small beer before strong, unless indeed they liked the small better; never to kiss the maid if they could kiss the mistress, unless the maid was prettier; with other statements of a similar kind.