What is the origin of "nerp" or possibly "nurp"

In the 1970s I asked a clerk at the lumber yard in Laguna Beach, California, whether I could have a hole drilled in a door hinge so I could put a set-screw in it. That would prevent the removal of the hinge, an action which would permit a miscreant to open the door even though it was locked.The clerk said, "So you want to have it nerped?" I have not had occasion to learn whether that word is still in use... or its origin.

Solution 1:

The clerk was saying (most probably) “So you want to have it NRP'ed?” rather than nerped. A NRP hinge is a Non-Removable-Pin hinge (1,2). Some styles of NRP hinges use a setscrew against the pin; others use a swaged-in-place pin (effectively a rivet); and some have bolster pins that project from the face of a hinge leaf into the face of the other leaf.