Bright Lights, Big City, by Jay McInerney (1984). Page 124:
“In the top drawer you discover two empty rectangular packets. Actually, one of them is not quite empty; inside the black paper is a fine dusting of white. You scrape it onto the desk with a credit card, using the edge of the card to rake up two clean lines. You look over at Megan. She’s reading. You could quietly hoover the lines and she’d never know the difference. You extract a bill from your wallet and roll it into a tight cylinder between thumb and forefinger. One apiece isn’t going to do much for either of you. On the other hand, two won’t do much for you, either; one will make you want another, and another will only initiate a chain reaction of desperate longings. Is this self-knowledge? In any case, you want to do something nice for Megan. For her it might be a treat, something out of the ordinary.
“‘Meg. Come over here a minute.’ Now you are committed.
“You hold out the bill. She raises her eyebrows.
“‘This will make you forget you didn’t eat lunch.’
“‘What is it?’
“‘The powder that made Bolivia famous.'”