from
Jargon File (4.4.4, 14 Aug 2003)
on the gripping hand
In the progression that starts "On the one hand..." and continues "On
the other hand..." mainstream English may add "on the third hand..."
even though most people don't have three hands. Among hackers, it is
just as likely to be "on the gripping hand". This metaphor supplied
the title of Larry Niven & Jerry Pournelle's 1993 SF novel "The
Gripping Hand" which involved a species of hostile aliens with three
arms (the same species, in fact, referenced in {juggling eggs}). As
with {TANSTAAFL} and {con}, this usage became one of the naturalized
imports from SF fandom frequently observed among hackers.