As a noun fum
is smoke.
As an abbreviation fup is
(internet) follow-up.
fum
English
Verb
(obsolete) To play upon a fiddle.
* Ben Jonson
- Follow me, and fum as you go.
(
Webster 1913)
----
fup
English
Abbreviation
(
Abbreviation)
(
en-abbr)
(Internet) follow-up