My sister in law thought that the Mrs. Doubtfire song from aerosmith was sung "Do the funky lady!" instead of "Dude looks like a lady". She even fought me and my wife on it and called us crazy until we showed her the lyrics online.

For example, I've been saying "for all intensive purposes" my whole life, only to discover the phrase is actually "for all intents and purposes".

Well imagine you (and all others who made such mistakes) instead of realising your errors, were able to influence others to adapt their mistakes?

Far fetched? Na.

People adapting those kind of errors is the reason why Americans, till today call;

petrol (a liquid) -> gas (wonder what they call the real gas for cooking ?)

trousers -> Pants (wonder what they call the real underwear pants ?)

Gear shift -> stick shift

football -> Soccer (American football is NOT football! Find another name for it)

Damn .... I used to have a longer list

American usage..
Gas, actually more accurate than your use of "Petrol" as both are shorthand.
Gas for Gasoline, which it is.
Petrol for Petroleum, which is used to make a variety of things.

Pants, shorthand for Pantaloons.
While Trousers were a different sort of leg-wear, each kept only one term.

Undergarments...
Underwear is generic for the category, somewhat gendered to the male but can be used for both.
Shorts is the legless or very short-legged varieties.
Long Johns are the full leg variants, and the etymology is debatable but tends to be credited to the outfit of similar make worn by a famous boxer.

Stick shift usually refers specifically to the rod itself, and the whole thing visible device is called a Shifter.
But the use on this one tends to be regional, and seems to be fully unknown in some areas here.

Football <-> Soccer, The Football Association,... it was formed in Britain, and brought to the colonies, and for some reason endured.

...
Some others..
Calling Coffee "Java" - because that is the name of one of the first plantations growing the beans.

Calling everything that involves power and rotates a Motor.. Not a Clue.

Going to THE Hospital rather than to Hospital. The lack is actually a carry over from the word coming in to use before the advent of the Places we call Hospital. Since they existed before the colonies, there was a The to reference.

Some of it .. I swear is confused just to be confusing...
Taps that serve potable water, are Faucets in the North, Spigots and the South, but those that provide water not fit for drinking are called Spigots in the North and Taps in the South.

Some of it .. I swear is confused just to be confusing...
Taps that serve potable water, are Faucets in the North, Spigots and the South, but those that provide water not fit for drinking are called Spigots in the North and Taps in the South.

Some of it .. I swear is confused just to be confusing...
Taps that serve potable water, are Faucets in the North, Spigots and the South, but those that provide water not fit for drinking are called Spigots in the North and Taps in the South.

I'm from the Pacific Northwest and I've exclusively heard "Faucet" regardless of potability or indoor/outdoor use. (Spell checker doesn't think potability is a word, but it totally is.)

"Faucet" on my kitchen sink.
"Faucet" outside that I hook my sprinklers to.
"Faucet" connected to a well.

"Tap" on a beer keg.

"Spigot" ... not used around here, but I'd think "Faucet" if someone actually said it.

We also use:

Drinking Fountain = Faucet that emits water upwards a few inches that lets you drink directly from the stream (or fill a bottle). Usually includes a basin to catch the water that you don't drink/bottle.

Fire Hydrant = 'Serious business' water supplies placed along the sides of roads that fire-fighting vehicles can connect to for high-volume, high-velocity water near the scene of a fire.