I don’t have a dog in this fight.
I burning your fight.
Huh. I have never heard “Shut the front door” used like that. Maybe it hasn’t made its way to central Missouri yet. Not much has made its way to central Missouri. I’ll get a jump on the trend and start hating it now.
I have heard the “rodeo” one once or twice. I don’t mind it, but I prefer “I didn’t just fall off the turnip truck”.
This one, though, will always be one of my first-string idioms. My mom always says it, and I picked it up from her.
There is also a grandfather in the next room who says “Franklin Delano!”. What is that supposed to mean?
I’m in Canada.
I’ve heard “shut the front door” but not the rodeo one. I don’t even know what that one means.
That’s because it’s not in your wheelhouse.
For a completely typical use of it, there’s this Castle clip. The actual phrase is at 1:10 in the video, but the full thing sets up the context for the usage. The connotation is very much more “no way!” than “shut up.”
Right! They’re selling some kind of cookies .. we don’t know what they’re trying to say, but it paid the wages at the ad firm. 
What if I actually want you to shut the front door?
And what if it actually ain’t my first rodeo?
Then someone will get all up in your grill.
This ain’t my first time to the rodeo, so don’t piss down my back and tell me it’s raining, or I’ll show you where the bull came through the buckwheat. What’s the West coming to, anyway?
What comes around, goes around.
“Ain’t my first rodeo” has been used around here for a long time. Of course, we actually do have rodeos. And both kinds of music.
I think I learned “if it had been a snake it woulda bit me” from my grandmother.
I’ve never heard “shut the front door”, but in my head it immediately sounded similar to “shut the fuck up” meaning “you gotta be kidding me”. But I think I’ve only heard that (STFU) maybe on TV or something, not IRL.
I don’t think that anyone who uses these intends to be witty or clever, and certainly not original. That’s kind of the point, in fact.
It is what it is.
At the end of the day.
Crikey O’Riley, and no mistake.
That is what it is.
This one confused me too.
“Fuckin’ A!” ??
?? IDK, it’s a stretch…
Is it possibly an exclamation like “Godfrey Daniel?”
You gotta be dry humpin’ me, dude.