they drank. they were drinking (and so the Imperfect tense throughout the verse). Note the Figure of speech Asyndeton in this verse (App-6), to emphasize the crisis of the flood.
Related Commentaries of Luke 17:27
Luke 17:27
27 They did eat, they drank, they married wives, they were given in marriage, until the day that Noe entered into the ark, and the flood came, and destroyed them all.