This statement refers to threads on a screw, nut, bolt, etc. To tighten, you turn to the right. A screw will bite further into the material or a faucet will be closed. To loosen, you turn toward the left. A screw will become unscrewed or a faucet will become open.
What Lefty and Righty refers to can be confusing. You can't technically turn things left or right. You turn things clockwise or counterclockwise. When you drive your car and make a left turn, which way do your turn the steering wheel to make it happen? Most people would say "left," when in fact you are turning it counter-clockwise. Same theory applies; the top of the wheel (or valve, or nut) goes to the left.
A few exceptions exist. To be 100% technically accurate, this only works on so-called "right handed" threads. Things that have "left handed" threads tighten when rotated counterclockwise and loosen when rotated clockwise. Some liquid propane tank connectors and some pipe fittings have left handed threads. Screws, bolts and nuts can also be found in left handed versions. It is safe to say that probably 95% of all threaded things out there do have "right handed" threads.
Ok, go grab a screw driver and give it a whirl! "Righty-Tighty, Lefty-Loosey"
This guy has done a good job with his video explaining and showing it...
Author: Charlene Bower