The "Air Lines Knot-Hole Club," pictured here, was "to kibitz the erection of the world's largest airline terminal."

The word "kibitz" is Yiddish for "spectator," though particularly one who might offer poor advice. The "knot holes," (perhaps referring to imperfections in wood grain) are viewing holes that allowed inspectors and other curious members of the public to check out what's going on beyond the construction fence.

In 2013, an iteration of these "knot holes" became a local law, stating that "every 25 feet, fences must have 12-inch by 12-inch viewing panels." However, the Airlines Terminal Building, completed in 1939, most likely placed them as an advertising gimmick to excite inquisitive New Yorkers.