“Mind your own beeswax”, came from the days when smallpox was a regular disfigurement. Fine ladies would fill in the pocks with beeswax. However when the weather was very warm the wax might melt. But it was not the thing to do for one lady to tell another that her makeup needed attention. Hence the sharp rebuke to "mind your own beeswax!"

Nails were once hand-tooled and costly. When someone tore down an aging cabin or barn he would salvage the nails so he could re-use them in later construction. When building a door, however, carpenters often drove the nail through then bent it over on the other end so it couldn't work its way out. When it came time to salvage, these bent "door nails" were considered useless or "dead."

Hence “dead as a doornail.”

We've all heard the phrase that something was done "half-ass," but few people stop to wonder what such a ridiculous expression could possibly mean. The term "half-ass" evolved from "half-adz." An adz is an axelike tool with a curved blade used for shaping wood. If you were wealthy and paid top-dollar for a new fireplace, the mantle would be shaped using an adz in the front as well as the back side, which isn't visible. However, if you weren't wealthy and wanted to save money, you could have only the front visible portion of the mantle shaped, this cheaper job being a "half-adz" job.