While he ate his sandwich and sipped his beer, a bit of conversation came back to him. Blaisedell, the poet, had said to him, "You love beer so much. I'll bet some day you'll go in and order a beer milk shake." It was a simple piece of foolery, but it had bothered Doc ever since. He wondered what a beer milk shake would taste like. The idea gagged him but he couldn't let it alone. It cropped up every time he had a glass of beer. Would it curdle the milk? Would you add sugar? It was like a shrimp ice cream. Once the thing got into your head you couldn't forget it. He finished his sandwich and paid Herman. He purposely didn't look at the milk shake machine lined up against the back wall. If a man ordered a beer milk shake, he thought, he'd better do it in a town where he wasn't known. But then, a man with a beard, ordering a beer milk shake in a town where he wasn't known--they might call the police.

-Cannery Row, chapter 17

A concoction served at Schnack, a restaurant on the border of Red Hook and Carroll Gardens in Brooklyn, it is, more or less, exactly what it sounds like. Beer is added to a chocolate or vanilla milkshake, creating a treat whose sweetness is accompanied by an undertone of bitterness, and, of course, alcohol.