Any object you can not describe because you are to stupid to remember the proper terminology OR a mechanical part that is machined for an unusual application and, therefore, not mass produced.
EXAMPLES: wing nut,
Can you grab me that drill, a #2 bit, two screws and that Fern Dobbler?
Well, here’s your problem, your Fern Dobbler is not aligned.
“Where is that thing?”
“What thing?”
“You know, that Fern Dobbler”