This is a list of humourous linguistics in various languages that I've encountered:
In America, if you want to split the cost of an evening out, you say you are "going Dutch," since the Dutch are well known for their frugality. The Dutch, on the other hand, call the same arrangement "op z'n Amerikaans" (going American) because the Americans are known for their egalitarian nature!
In English, the bird "turkey" was named as though it came from Turkey. In Turkish, the bird is named "hindi" as though it came from "Hindistan," which is Turkish for India. (Any Hindi speakers wish to comment on the Hindi name of a turkey?)
Also, in Turkish, the word for cannibal is "yam yam," pronounced "yum yum" as if it tasted good. Really.
French fries aren't really French. In fact, they were invented by the English (so greasy, you know), who call them chips. The French call them "pommes frites" or "fried apples [of the earth]."
In Wien (the German name for Vienna), they like to eat Frankforters. In Frankfort, they eat the same thing, but call them Wieners.