expression, godan verb (-mu)
drink straight; drink neat
Used specifically for drinking spirits such as whisky without adding water, ice, or mixers. The phrase is a set expression combining 生 (here meaning 'undiluted' or 'straight') with 飲む.
彼はいつもウイスキーを生で飲む。
He always drinks his whisky straight.
この焼酎は生で飲むのが一番おいしい。
This shochu is best drunk neat.