(emphasis added)
…but I like the way you think.
Hey, I totally missed that. But it still made sense 
Likewise, growing up in Northeast Ohio, I always wondered why everybody said sherbet /(ˈʃɜrbət/) with that intrusive r in the second syllable: /ˈʃɜrbərt/, since it wasn’t spelled that way. Or for that matter the intrusive -r at the end of lozenge: /ˈlɑzəndʒər/, which sounds even weirder as it adds an extra syllable.
They do that in Beijing dialect of Mandarin, I’ve read: they change the coda in each syllable to -r. So that in “You owe me san (3) yuan” it would come out “sar yuar.”
Oh good fucking god, just spoiler the goddamned explanation, I’m an idiot. I got “Shitcago” (I think) from the last one, but I have no idea still.
ETA: :smack: OK, OK. I got it. I wrote “instrustive.” Well played.
For the same reason we add an r to colonel – because to pronounce such words like they are spelled would just sound weird.
Apologies! Wasn’t trying to be coy. You should have totally stuck an extra ‘T’ in there sometwhere while you were editing.
My boss is native NH and says “aunt” the same way as “aren’t” and garage as gararge. And sometimes “idear”.
In East TN it’s Worshington and worsh.
Australia and New Zealand are great for putting an R at the end of any word that ought to end in ‘A’
They’d say I’m in Canader.
Common in Eastern Nebraska, where I grew up.
I have known two people who are full-on the extremes in “r” adding/removal. One from Boston who definitely says “Warshington”. (The one that kills me is saying “idear” when presenting a paper.) The other from near NYC who is an actual Baba Wawa type. Getting asked if she could borrow a quarter required major laugh stifling.
A variant that may occur is “Whashington”. Not sure if the origin is Southern Plains or Intermountain West (or in between).
Hee. Maybe she also starred in Rural Juror.
You might not hear it, but there is a slight difference between the typical New England pronunciation of aunt and aren’t. Not sure how to describe it, but the first word is more of an AW sound for the “au” and the second is more of an AH sound for the “are”.
But this is a different speech pattern than the one mentioned in the OP.
I think that nearly everybody, everywhere does that. For unknown reasons. They do it here in Washington state.
How about “intrusive S”? There is a town nearby called Leavenworth, and I have encountered a number of people who say “Leavensworth”. I’ll note that most of the people I’ve heard do this have had vague “southern” accents - a lot of my area was settled by “Arkies” many decades ago.
Funny, I always thought it was pronounced: sor-BAY. 
The best idea for why it happens is that it goes from a non-rhotic dialect, which essentially drops the R sound, but then went back to rhotic, and started inserting Rs in places where theyu weren’t originally. So it’s hypercorrective.
Linking R is just because, since the final R sound has no meaning, it just becomes a natural way to separate vowels. Those in rhotic dialects tend to use the glottal stop, since it has no meaning in English (except in a few words like uh-oh). But there are other languages where the glottal does have meaning.
How is it not “What’s the deal with the “r” added in certain words?”
I will have to listen more closely to learn the difference, thanks! I say “aunt” like “ant”, nothing like “aren’t”.