Still not quite... A PANDA is a specific URL(web address), that when entered into the web address bar in your browser window, would
Preview
And Accept a HIT,
rather than only previewing the HIT without accepting it.
A PANDA basically is a web address that is a shortcut way of accepting a HIT without the extra step of previewing it first. The actually web address would have the phrase "Preview and Accept" embedded in it, and back in the day, a Turker would simply modify the web address with the Requester or HIT information. I jumped into Turking in 2016, so when I was getting started I used TurkMaster, which is a script that enables easily making PANDAs for different individual HITs or batches...
The act of PANDA'ing something means to repeatedly refresh that "Preview and Accept" web address (corresponding to the HIT or batch you're after) in an attempt to catch one HIT, or several HITs, very quickly. PANDA Crazy and MTS's HIT Catcher perform the process of PANDA'ing for us now. In MTS, a Watcher is an automated
PANDA'er... If that makes sense.
Since the "Preview and Accept" web address is no longer valid and doesn't work, it's not accurate to use the term PANDA... but a lot of us still do, because pandas are awesome.