干杯 (gān bēi) literally means 'dry the cup' — the Chinese equivalent of 'cheers!' or 'bottoms up!' In formal banquets, people really do empty their glass.
usage
杯 works both as a noun (cup) and as a measure word (a cup of). Context tells you which: 这个杯 (this cup) vs. 一杯茶 (a cup of tea).
