I have heard before that ありがとう came from the word "obrigado" in Portuguese. Is this true and is there any evidence to support this, or is it an old wives' tale?
Where did とんでもない (meaning "not at all" or "outrageous!") come from? Could it be 飛んでもない ? ("will not even jump/fly" in a similar way how "When pigs fly" is considered a remark for something ...
Topic. I've heard/seen somewhere that 被【かぶ】る was "gairaigo-fied" (?) from the English word "cover" (similar to ダブる or デモる), and then presumably given ateji from 被【おお】う since the meanings overlap so ...