Twindexing

Twindexing refers to the behavior of holding the tips of just one's pair of two index fingers prominently together, or tapping them together repeatedly.

Etymology
The portmanteau is constructed by blending the word "twin" indicating BOTH are being used, as opposed to a gesture with just one of the index fingers.

It should probably not just be called "indexing" since there are other gestures involving a single index finger, such as indicating the number one as a quantity, or to indicate someone has an idea.

Those could probably be called monoindexing or unindexing (to indicate quantity) and ideaindexing for revelations.