spare at the spigot, and let out at the bung-hole

The meaning is explained in quot. 1721. The spigot is the peg or pin used to regulate the flow of liquid through the tap on a cask, while the bung-hole is the (much larger) opening through which a cask is filled or emptied and which is closed by a plug (the bung).

1642 G. TORRIANO Select Italian Proverbs 50 He holdeth in at the spicket, but letteth out at the bunghole.

1670 J. RAY English Proverbs 193 Spare at the spigget, and let it out at the bung-hole.

1721 J. KELLY Scottish Proverbs 299 Spare at the Spiggot, and let out at the Bung Hole. Spoken to them who are careful and penurious in some trifling Things, but neglective in the main Chance.

1885 E. J. HARDY How to be Happy though Married xiii. People are often saving at the wrong place... They spare at the spigot, and let all run away at the bunghole.

1935 H. ZINSSER Rats, Lice & History xvi. It is all a part of the strange contradictions between idealism and savagery that characterize the most curious of all mammals. It leads to the extraordinary practice of what is spoken of as ‘saving at the spigot and wasting at the bung’.

1966 L. BEERS Wild Apples & North Wind xxvii. That might fix it now, but next summer you’d be in as bad a squeeze... If you save at the spigot you lose at the bung.