
OCD explains at the beginning of the thread that IBTanked sends their tanks out to customers inside of clear plastic bottles with caps. Just another way to protect the tanks during transit. I believe the daughter had been holding one of these bottles, opening and closing the cap when someone asked what was she doing. She replied that she was fiddling with the thingy. It became a family inside joke.
What they discovered by accident was placing a juice filled tank inside one of the "thingy's" and "fiddling" with it, ie opening and closing the cap, air bubbles could be seen leaving the holes of the carto and rising up through the juice in the tank. Doing the "fiddling the thingy" seems to prime the carto due to changing the air pressure within the "thingy".
Whew!! That story was more difficult to tell than when I remember reading it...