Geek speak is how the uninitiated refer to the jargon and special vocabulary used by those immersed in computers and other fields of information technology. Geek speak is usually something that someone else uses. (That person may be viewed as a geek or just someone who knows more than you.) As a person learns about computers, the terms they use become familiar and only the ones they haven't mastered yet continue to be geek speak. The term was used in press coverage of the 1998 (and ongoing) Microsoft antitrust case in which a great deal of industry jargon was heard from witnesses and in e-mail introduced as evidence.
Geek speak often sounds like normal English that doesn't quite make sense because familiar words have been given a new meaning. A port is no longer where a ship docks and a spool is no longer what thread comes on. And for that matter, a thread is no longer a thin strand of cotton. And executing a program is not at all the same thing as killing it.
A special branch of geek speak is chat acronyms.