The creators of the format pronounced GIF as
"Jif" with a soft "G” as in "gin". Steve Wilhite* says that the
intended pronunciation is meant to echo the American peanut butter brand,
Jif, and CompuServe employees would often say "Choosy developers choose
GIF", spoofing this brand's television commercials
*Steve Wilhite of CompuServe was the engineering lead on the team that adapted the GIF file formatsources
http://www.i-mockery.com/minimocks/clash-of-the-titans/5.gif