With regard to 'Double Dutch', as I mentioned above, perhaps I spoke too soon.German isn't much easier. I'm surprised, no one posted such a saying with German.
cameo~ is the phrase "it's spanish to me" is realli used in taiwan? lol. so it would be 跟西班牙語一樣? andd, is the phrase 跟天書一樣 (like a heavenly script/book) used a lot?
I've personally never heard the "Spanish thing". Maybe that's just something between you and your friend; it's probably not a common phrase in Taiwan.1. As you can see I'm from Taiwan.
2. We say "It's all Spanish to me."
3. I don't know why. Maybe my fellow Taiwanese can give us a reason.