ShadowXIX:
After checking around some websites - mainstream, left wing and underground - that promote unrestricted open discussions, which also allow for and/or include the advancement of conspiracy theories; and after carefully viewing the comments posted in those forums, it is abundantly clear that the alleged intentional controlled demolition of the World Trade Centers has once again become a popular topic - and as such has initiated questions such as yours. In fact, some members who frequent those websites, who are in opposition to the controlled demolition conspiracy theory, have strongly urged inquisitve minds to post the "What does 'Pull It' mean?" question on firefighting discussion sites such as this and to simply ask a firefighter.
Firefighters in the older, centuries old towns and cities that are very deep and rich in history and tradition know from records, logs, or for years and years have heard stories about the 'old days' and can - usually - easily explain terminolgy and slang from previous eras that's still very much used today. The origins of these terms really are no mystery to any firefighter who cares about his history. Words and terms in firefighting are used every day without any thought to their origin; fire 'plug' is an example. There'a a reason some call a hydrant a plug.
Same is true for "Pull It" and some of the other terminology conspiracy theory people now think means to demolish a structure. "Pull It" does not mean that to firefighters with knowledge of history or to those serving in departments with deep, rich histories.
As I explained in my above post the term in question, "Pull It" comes from 'back in the day' where the fire hose would be pulled to signal to the interior crew that they must egress the structure asap. It is a very old term. It's from the horse drawn and steam powered fire engine days - but is still used today by many. In no manner shape or form on NineEleven - or at any other time - does "Pull It" have anything to do with controlled demolition.
OVD