Green’s Dictionary of Slang

(Asian Eng.) a serving of San Miguel beer.

1957		R. Mason World of Suzie Wong 36: She picked up the beer bottle on the table and drained it into my glass. ‘You would like another San Mig?’.
1963		I. Fleming Thrilling Cities (2009) 15: The initiation ceremony requires the consumption of sixteen San Migs, which is the pro [i.e. prostitute] name for the local San Miguel beer - to my taste a very unencouraging beer.
1984		E. Dodge Dau: A Novel of Vietnam 61: ‘If he’s going to shit,’ explained Jacques, wrinkling his nose, ‘he might as well shit San Migs’ .
1994		F. Viviano Dispatches from the Pacific Century 53: [T]hey drank San Migs and swapped tales about Manila.
2002		D. Way General & Mr Tu 216: A group of Royal Navy matelots sat on stools at the bar counter with San Migs.