back-of-a-fag-packet en · ADJ
Etymology
See fag (“cigarette”).
Meanings
-
(UK, not-comparable, slang) Synonym of back-of-the-envelope.
[…] back-of-a-fag-packet calculations concur: the areas of the Maltepe and Yenikapı parade grounds are roughly similar […]
2019, Hannah Lucinda Smith, Erdogan Rising: The Battle for the Soul of Turkey: