The eggplant is possibly the most obviously poorly named fruit or vegetable, neck-and-neck with the pineapple. Its name came from the fact that some cultivars used to be white, and better resembled eggs than the purple variety today. However, before they were called eggplants, they had another name in English: mad apples. It was believed that eating the eggplant would cause insanity, and so they acquired the names of mad apples and rage apples.
(As for the pineapple, it comes from the fact that pine cones used to be called pine apples. Pineapples resembled pine cones, and the name was used for them, and persisted long after it stopped being used for the pine cones themselves, hence why pineapples have no connections to pines nor apples.)
Traditionally, Christians are not supposed to eat meat on Fridays, but fish is acceptable. However, the temptation often proved too great to resist, and a number of loopholes were developed to get around the rule. Perhaps the most unusual of these was the belief that barnacle geese spontaneously generated from driftwood. Since this made them not proper birds, they could be eaten on Fridays. At the Fourth Council of the Lateran in 1215, Pope Innocent III had to explicitly forbid eating barnacle geese on Fridays, saying that whatever their origin, they lived and ate like other birds, and so were to be considered birds.
In Medieval Europe, one could not promote a pawn to a queen unless there was no other queen of that color on the board. The reason for this rule was so that the king would never be guilty of bigamy by having two or more queens concurrently.
The reason why it’s traditional to carry the bride over the threshold dates back to the Rape of the Sabine Women. When Rome was first founded by Romulus and Remus, they mostly attracted the dregs of society, those without connections or families. Consequently, there was a dearth of women available to the first Romans. In order to rectify this, Romulus invited the Sabines to a festival and, upon a given signal, the Romans fell upon them, capturing their wives and daughters and bringing them back to their homes unwillingly. It is this event that is commemorated by this wedding tradition.
It was thought that ghosts appeared to the living in the way they looked when they died. According to Roman tradition, a white burial shroud was placed upon the body at death. This is why the traditional appearance of a ghost is of a body under a white sheet. This Roman connection applies to more than just appearance. It was also though that ghosts spoke Latin, as can be seen in Shakespeare’s Hamlet.