grumbler, n. — Green’s Dictionary of Slang

grumbler n.

[the landlord grumbles at the customer’s economy; the drink makes one’s stomach grumble]

fourpennyworth of grog; thus a small portion of strong alcohol.

1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc.
2023		R. Milward Man-Eating Typewriter 113: I’d spike Herman’s lemonade with shushed grumblers.