My (non-native English speaking) boyfriend recently had an epiphany (which I find hilarious). He was reading something that said “a gust of wind” and got really excited about it. He’s been hearing people use the phrase for years; however, he had never actually seen it in print. Apparently, he had always assumed that it was some bizarre, mildly poetic English phrase…“Augusta wind” as in Augusta, Georgia, or something along those lines.
That’s kinda cute… don’t tease him too badly.
This Canadian girl at work years ago had a malapropism like this that used to drive me insane. You know when someone gets a common saying wrong, but they like it and use it incorrectly all the time? Arrgh!
She liked the phrase “for all intents and purposes” but she would always say it as “for all intensive purposes”, which makes no sense at all! As she was my boss I didn’t see fit to correct her, I just ground my teeth into dust instead.
I knew a transcriber some years back who tried desperately to make sense out of the word “entrepreneurial,” which she’d clearly never heard of – and came up with what still makes perfect sense to me: “intrepid oriole.”
Kind of the reverse, but it works. And rather well, at that. 
I worked with a woman who came from Yugoslavia.
Her english was excellent, just excellent. No communication worries. But when she was frazzled she would mix her metaphors.
Our favorite, one that we razzed her for years on, was mixing “Going to hell in a handbasket” and " I’m a nervous wreck."
She said, " I’m a nervous basket."
Oh GOD, I hate that one. But I’ve heard/seen Americans who grew up speaking English do it, so I don’t think you can blame it on her northern origins.
Actually I can as I’m Australian - you’re ALL northerners to me