At the bottom of Hill Hill

Also Mexico's "Yucatán". When the spanish came and asked what the place was called they answered with "Yucatán" wich litteraly means "I don't understand you".

Sahara Desert

Koi carp

I can't remember which Discworld novel it is but in one of them is a paragraph about this. There, Terry Pratchett speculates that a lot of mountain names probably just mean "that's a mountain, you idiot" in the local language.