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Does the English ‘shade’ come from the Hebrew/Aramaic shaid, demon? It seems a logical leap from demon to spirit to ghost.
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Whence comes the phrase, ‘to get one’s ashes hauled’? I can’t think of a more unlikely euphemism for sex.

For #1, the answer is no according to the OED. It cites Middle English “schade” and Old English “sceadu.” Note, however, that in the three pages on the word “shade”, there are a few senses that actually refer to ghostly things: “The visible but impalpable form of a dead person, a ghost. Also, a disembodied spirit, an inhabitant of Hades,” “A spectre, phantom,” and “in humorous invocation of the spirit of a deceased person …”
In an old-fashioned fireplace, in a house with a basement, you’ll find an ash door - a little hatch in the bottom or back wall of the firebox where you can shove the old ashes before building a new fire. The ashes accumulate in an ash bin, which has a cleanout door in the basement or on the outside of the house. When the bin is full, the conscientious homeowner will empty it, or call a professional to get his ashes hauled.
Those who cling to the notion that semen builds up dangerously when men don’t get enough sex will similarly hire a professional to remove the excess. The metaphor can be extended to those who don’t believe anything other than frustration is accumulating, as well as nonprofessional sex. It’s pretty consistent in being applied to a workmanlike physical release, rather than a romantic encounter, so it’s a bit rude (though sometimes humorous) to say it about sex with your wife.
. Trying to connect words(which sound alike) from two different languages usually leads to incorrect conclusions.
Just for context–it first appears in the US around 1900.
Well put. My favorite example is Spanish caos (“chaos”) and English cows.