Here's something that happens here all the time, and it DRIVES ME INSANE. Im not sure if this happens in America, but here, its very common.
"If I'd had the money, I would've bought it". When people speak those words (or similar), it sounds like just like that. Would've. However, when they type it or write it, they type it or write it like this:
"If I'd had the money, I would of bought it".
I dont know if its ignorance, a bad education or laziness, but a hell of a lot of people here think 'would've' is the shortened version of 'would of', rather than 'would have'.
Something else that gets on my titt1es here is when people say 'I bought it off my friend', instead of 'I bought it from my friend', or even worse, 'I brought it off my friend'

But for me, the worst Englishism (or the one that drives me insane most of all) is what I call 'turnarounditis'. Its some sort of physical compulsion people experience before they do anything.
"I told my friend he was ugly and he
turned around and punched me in the face". "I called the bank to find out my balance and the girl
turned around and said I'm £15.51 in credit". "I confronted my boyfriend about whether he'd shagged the girl next door and he
turned around and denied it".
Before doing anything, a lot of English people actually do a 360 degree turn. They are the European version of the Whirling Dervish.