crook one's elbow

Also, bend one's elbow. Drink liquor, especially a great deal. For example, Bill is known to crook his elbow now and then, or Uncle Joe rather overdoes it with bending his elbow. Both slangy expressions allude to the motion of lifting a drink to one's lips, which involves bending the elbow. The first dates from about 1820, and the second from about 1900.