“Pop” seems to be the word used to describe any visual characteristic that you wish your coral had.  There is no basis in coral health.

The idea seems to be magnified by looking at DSLR camera photos.  I’ll paraphrase an actual thread on the topic:

Zowie! Zowie! LED’s will pop your corals!

The only way I can show you is through a DSLR camera.

Worth linking in our “DSLR Camera” article about now.

Supposedly the term “pop” has some actual artistic meaning in unrelated industries.

Entries in the Internet Reefer’s Decoder Ring are terms you’ll find in the course of online discussion about reefing that make very little sense.   In some cases, these terms seem to have been borrowed from another industry where the term did have meaning, but the meaning did not carry over to reefing.