Yahoo’s Associated Content confirms what I had previously heard about the expression; it began when Roman soldiers were paid with salt. The word “soldier” literally meant “one who is paid in salt.” The pay was either made directly in salt or in “salarium,” which was an allowance for purchasing salt and is the origin of the word “salary.” A person is said to be earning their salary if they are described as being worth their salt. Biblical references for salt usually had positive meanings, such as when Jesus called the disciples “the salt of the earth.”

There is no dispute that this expression is used to describe a cheap or misery person. However, we have choices for the origin. World Wide Words says the word “skate” was used to express contempt, and it evolved into “cheapskate” in the late nineteenth century. The term was originally used to describe a worn-out horse, a mean or contemptible person, or a second-rate sportsman. Wiki answers has two other possible explanations for the origin, and both are more colorful. One is that skates that strapped onto your shoes were so cheap that they often fell off, and were literally cheap skates. The other is that in the early 1900’s there was a panhandler named Kate Robinson who inherited a fortune, but continued to beg. Thrifty people were told “you are as cheap as Kate,” which when said quickly becomes “cheapskate.” My vote is that the last explanation is the most interesting.

The Phrase Finder says that the expression means someone is talking nonsense, and that they are pretending to have knowledge on a subject on which they are ignorant. Reference is given to Farmer and Henley Slang and Its Analogues, 1888: “Dis is only a bluff dey’re makin’ – see! Dey’re talkin’ tru dere hats.” The possibility is raised that the expression originated from the practice in the UK parliament where you had to be seated and wearing a top hat to raise a point of order. This is followed by “topping,” or “talking out a bill,” which means filibustering with rambling nonsense. However, it is pointed out that stories about top-hatted members of the UK parliament becoming a dominantly U.S. expression doesn’t seem to be likely. There is speculation the idiom originated from men holding their hats over their faces while pretending to pray. I think it is more likely that it is a variation of “talking off the top of your head,” where an empty hat would set, which means you are speaking speculatively without much knowledge.

World Wide Words says this phrase was used in several Bible passages and by Shakespeare, but that it has been around “as long as the language.” The first recorded example was in the words of King Alfred at the end of the ninth century. Sight is considered to be precious, the pupil of the eye was called the apple, and to be called “the apple of my eye” was considered the highest form of endearment. The Latin original for pupil was pupilla, or “little doll.” “It was applied to the dark central portion of the eye within the iris because of the tiny image of oneself…that one can see when looking into another person’s eye.”

The Phase Finder describes this idiom to mean you have had a happy experience that has caused you to flush with pleasure. The expression apparently originated from observation that emtional pleasure causes the same kind of flushing of the face created by physical tickling. I recall reading that tickling can become tortorous if carried too far. The companion expression “tickled to death” is used to descibe someone who could not be happier, but the literal meaning is that someone has been tickled to the point breathing becomes difficult. The term “tickled to death” appeared in the St. Nicholas childrens magazine in 1907, and the term “tickled pink” was used by an Illinois newspaper The Daily Review in 1910. For those who want a scientific explanation, the flush (or a blush) is caused by an emotional response that tells the brain the tiny vessels in the face need more blood.

The community.livejournal says this idiomatic expression is used to describe something that pleases you or strongly engages your interest. As I expected, it is also a euphemism for sexual interest. “Tickle” means a spontaneous excitement such as when someone is physically tickled. “Fancy” can be a notion or whim. The expression was used in Abraham Tucker’s 1774 In the Light of Nature Pursued, with a passage about animals “…whose play had a quality of striking the joyous perception, or, as we vulgarly say, tickling the fancy.” The expression went even further to the vulgar side after World War II, when the slang for a male homosexual “Nancy” was noted to rhyme with “Fancy.” An alternate is “strike your fancy.”