A nonsense word invented by a radiocomedian of the 1940s, meaning a (usually technical) part of some machine or device that he didn't really understand or know the proper name for.
Friend: "Yo, What do you think about this retro neon raincoat bro?"
You: "Aaaaahaha bro that narsticle rainshnizzle is pre fraish."
Friend: "Thanks brah"
You: "Nar Nar"
Fravis is a term for garbage or junk that comes in a number of pieces, often but not necessarily particulate, such as lego strewn all over the floor. In common use, according to very wrong people.
The crimp in the wax ring caught a bunch of fravis going through and ended up clogging the toilet.