What’s your vote for the most ridiculous, overpriced, and useless tweak?

My vote: Furutech Outlet Cover 105 NCF $220, with “special crystalline material that has two “active” properties.” https://www.thecableco.com/outlet-cover-105-ncf.html

"As I just got through saying you cannot reverse power cords either, obviously. Duh!"
Too late! So, that is what all those sparks were about?
FYI, changing the direction of IC cables don't guaranty the sound will be different. Almost all stranded wires are mixed up in both directions. Mixed up directions of strand wires can be 20:80 or 50:50. Only very high end cables are in one direction in stranded wires.  Almost people won't hear the difference in 80:20. 
Every high end cable manufacturers make mistakes very often. Putting 20~100 thin wires in same direction in a cable is very hard. I have found many high end $$$$ speaker, PC, and IC cables are made wrong. 
Alex / Wavetouch audio
It doesn’t make sense that stranded wires are not all in the same direction if the manufacturing process is automated - even without going to the trouble of controlling directionality. Do they dump all the strands in a barrel and pay some guy to grab them one by one? Give me a break! If it doesn’t make sense it’s not true. 

It certainly doesn’t hurt to try reversing interconnects, no matter whether they’re stranded, shielded, unshielded, whatever. Besides, there are other reasons why there’s no guarantee that reversing cables will be audible. We all know what those reasons are, don’t we? 😬 The big boys control the whole process from A to Z, so that interconnects, speaker cables, power cords, HDMI cables will be in the correct direction as marked. It’s not rocket science.

Of course, anyone can ignore directionality, it’s no skin off my nose. It’s just one of those small and sometimes irritating things that separates the high end from everybody else. One wonders, how long it will be before people get smart and control directionality for transformers, internal wiring of components and speakers, capacitors, resistors, ribbon connectors, etc.?
I’m a little surprised none of the tweakaphobes has mentioned the Quantum Clip. The Re-animator. Hey, If this is going to be a remedial class for advanced tweaks so be it! And the Clever Little Clock chopped liver, I suppose?

Nobody can understand what he cannot at first, or be it at last, imagine as a possibility... Alas! An answer for a question we never ask for, seems to some of us like an insult...But why not trying,experimenting and going for the unexpected ? Tweaks are only fun and rewarding if you make them for yourself... It is not necessary to buy anything, only to create for yourself...