The first word I decided to look at was アルバイト. To an American, it makes no sense that the word for "part-time job" would be アルバイト. Similar to words like ピエロ(clown) and ホッチキス(stapler), アルバト's origins seems mysterious. In actuality, アルバイト derives from the German word for "to work,"
arbeit. The word アルバイトis used frequently in Japan and reflects Germany's strong influence on the country during World War II. Several German words are now used in the Japanese language. ヒュッテ(mountain hut) comes from the German world
Hutte. A more striking example is the word
rommel. The word means victory/success in Japan and is based off newsreels reflecting the victories of German General Erwin Rommel during World War II.
The second word is バイキング which you would assume means "viking," but it really means "all-you-can-eat." The word is used commonly to reference Japanese buffets. It originates from "Imperial Viking," the name of the first buffet restaurant in Japan. It also plays on the stereotype that Vikings were extremely heavy eaters. I think that this was a good naming as it invokes the stereotypical image of a viking stuffing their face. The Japanese must have loved the name as バイキング has been become a part of their daily vocabulary.
It is interesting to note that many of these Japanese loanwords have been borrowed and then reinterpreted to fit the Japanese culture. Where as
arbeit typically refers to full-time empolyment, アルバイト only refers to part-time work. The case is even more extreme for バイキング.
Sources:
http://www.tofugu.com/2009/06/25/strange-katakana-words/
http://en.wikipedia.org/wiki/Loanword
http://www.japanese123.com/arubaito.htm
http://en.wikipedia.org/wiki/Germanism_(linguistics)#Japanese