The act of engaging in behavior which focuses on an object or circumstance peripheral to the immediate object or circumstance at hand.
The act of herp-nerding essentially introduces an extra element of humor by slightly derailing norms by focusing on something that doesn't need to be focused on, making it the new topic of focus. This act alters the attention from the immediate focus, to a peripheral focus.
(ex 1): Two individuals sit in a restaurant looking over a menu. This is the (normal) immediate object or circumstance at hand.
Herp-nerding would ensue if one or both of the two individuals were to take the menu, the silverware, and all objects on both sides of a table and attempt to match them up equally, as if each of the objects on both ends of the table were mirror images of one another.
The focus (and act of herp-nerding) would shift from reading the menu and ordering food, to mirroring the objects--the focus changed (from reading/ordering food) to (playing with and mirroring the objects on the table).