The Middle English Dictionary identifies the word seurgate ("sewer-gate") in a 1403 text, and, soon after that, other sources show souer, seuer, and finally sewer emerging to describe channels for carrying away waste and drainage. All of this comes from the Anglo-French word sewere, which is from Old French sewiere or seuwiere. That's thought to be a pretty mangled borrowing from the unattested Gallo-Roman word exaquaria, which meant something more like "drain". The Latin roots there are glaringly obvious (and present in multiple English words): ex-, meaning "out", and aquarius, "pertaining to water" - so water is flowing outwards. Ex- is from Proto-Indo-European eghs, also "out", and aqua derives, through Proto-Italic akwa, from another PIE reconstruction, hekweh​, which still meant "water".

Today, the word coquettish is basically a synonym of flirtatious, and that adjective comes from the rarer noun coquette, which was specifically a flirtatious woman. Earlier, however, coquette could refer to a flirtatious individual of any gender, and when the term was borrowed from French coquet, it meant "male flirt" (so the associated sexes slowly swapped over time). Here it gets even more interesting: coquet literally means "little cock" (as in the rooster), because of the belief that male chickens strut in a pompous, provocative manner. Coquet is a diminutive of the word coq, which in Old French was spelled coc (the etymon of our word cock), and that in turn comes from Latin coccus and Frankish kok, with the same definitions. Beyond that, the term is probably imitative of the cry of a chicken, perhaps by way of Proto-Germanic kukkaz​.

On page 22 of Kurt Vonnegut's darkly whimsical novel Breakfast of Champions, he claims that the word beaver meaning "vagina" originated among news photographers, who used it as a code word to tell other men that you could see up a woman's skirt from that angle. I don't know where he got that from, but I can't find any sources on that. The euphemism seems to trace back to 1910s British slang, when it referred to a man's beard. By 1927, due to the visual similarity, the definition got extended to female genitalia. The "beard" meaning emerged because of a resemblance to beaver pelts, and that word goes back to Old English beofor. Even earlier, beofor is from (through Proto-Germanic) the Proto-Indo-European root bher, meaning "bright" or "brown". Usage of beaver in language over time peaked in the 1850s, and the Vonnegutian definition is, in conclusion, erroneous.

Meh is the ultimate expression of boredom and disinterest. Phonetically, it's one of the easiest sounds we can make, involving a simple parting of the lips and expulsion of air through the mouth and nose. With that in mind, it seems like a word that's been around for a while and has changed very little throughout history. However, there's a lot more to meh than meets the eye. It turns out that the term has only been around in pop culture since 1991, when Lisa from The Simpsons used it and spelled it out the episode "Homer's Triple Bypass". Prior to that, there were a few scattered attestations, but that moment really tipped the scales. Some etymologists theorize that meh further derives from Yiddish mnyeh, which served a similar puropse, but beyond that not much is known. The word meh has been increasing in usage since the 1940s.

All etymologists agree that the word fanfare was borrowed from French a little bit before the turn of the seventeenth century, but then things get fuzzy, with two plausible explanations. Some claim that the word is imitative in origin, and that the story stops there, but others claim that the term traces to Arabic farfar, which meant "chatterer". This would have been borrowed by way of the Spanish or Italians and also explains the origin behind French fanfaron, meaning "boaster". Before that, the term is also echoic, so there's onomatopoeia involved either way. Usage of the word fanfare over time peaked in 2003 and, per Google Trends, search interest has been decreasing over the last fifteen years. Of course, there is no connection to either the terms fan or fare​.

When the game ping-pong was invented in England at the end of the nineteenth century, it was played with champagne corks and called whiff-whaff after the sounds made when they were hit by a paddle, but later on people switched to using celluloid balls, and since the sound changed the name did too, to reflect the new noise. In 1901, a British manufacturing company saw an opportunity, so they trademarked the name, and later on that was bought by the game production company Parker Brothers. There have been some myths that the name ping-pong is culturally insensitive because it makes fun of Chinese and we should use table tennis instead, but that's apocryphal. The real reason people say table tennis is because other manufacturing companies couldn't use ping pong so they marketed the generic term instead, which is pretty interesting.