Once Hercules slayed the Hydra, he dipped his arrows in the Hydra’s blood. This made his arrows poisonous.

In the Chinese theory, it stems from either “kôe-chiap” or “kê-chiap”, both from the Amoy dialect, where it means “the brine of pickled fish or shellfish.”

from http://masterblog.front.lv/category/fun/

As for the “eggplant sauce” theory, ”ketchup” derives from a Chinese word composed of two characters (茄汁), which means “eggplant sauce”. The first character (茄), meaning “eggplant”, is also the root for the word “tomato” and the second character (汁) means “juice” or “sauce.”

The Malay theory states that the English word originates from the Malay word kicap (or, kecap, ketjap), which translates to “fish sauce” – which is borrowed from the Chinese, anyway…

European-Arabic Theory:  E.N. Anderson, an American anthropologist, claimed that ketchup comes from the French escaveche, meaning “food in sauce”  (imagine… French ketchup!) while culinary historian Karen Hess traced it back to Arabic iskebey, or “pickling with vinegar”.

Blue Label Ketchup 1898, from wiki article

Playing Cards originated in Asia and spread across Europe around the 14th century. It arrived in England a little later than in Spain, Italy and Germany.

“Essentially, the Italian versions of early cards used the suits Cups, Swords, Coins and Batons – which, on migration to England, became Hearts, Spades, Diamonds and Clubs. The image for Spades on English and French cards looks somewhat like that of the German Acorn or Leaf suits, but its origin is revealed by its name rather than its shape. The Spanish and Italian for sword is ‘espada’ and ‘spada’ respectively, hence the suit ‘Swords’ became anglicized as ‘Spades’.”

So where does the non-card-playing meaning come from? It is an Americanism:

First of all, the phrase isn’t found before the 1920s. Damon Runyon, an American journalist and writer, used the expression that way in a piece for Hearst’s International magazine, in October 1929:

“I always hear the same thing about every bum on Broadway, male and female, including some I know are bums, in spades, right from taw.“

Some other spade phrases: “cocky as the King of Spades”, “call a spade a spade”, “spade something up”

“To kick the bucket, to die.”

Although there is not much evidence to support it, one theory as to why the phrase originates from the notion: people hanged themselves by standing on a bucket with a noose around their neck and then kicking the bucket away.

The word Skullduggery has been used to title various things from a 1970s Burt Reynolds film to the University of Adelaide orientation week, established in 1896.  

The origin dates back to 1910 and originally meant “without preparation,” referring to the ease of making a dish of cold turkey. In 1922, the expression acquired its darker connotation related to drug withdrawal.

Example: “That horse is a real daisy.  She’s well worth the price!”

Other etymological sources suggest it derives form the nickname for the Dusenberg, a luxury automobile introduced in the US in the 1920s.

A third possibility is that it come from the nickname given to Italian actress Eleanor Duse, who made headlines as beautiful and talented import to the New York theater world in the 1890s.

The definition has expanded in modern parlance from indicating something or someone superior to also including something that is extraordinary in its negative qualities.

Example:  ”That test was a real doozy.  I sure hope I passed.”