Well, try not to touch anything while your in my head Pinkie. Not only do I need my brain semi working for school, there is some stuff in my head that is not safe for ponies. Just trust me on this one....
Actually, the thing in my brain is NOT Pinkie Pie. It is an image of her strictly limited by MY perception and opinion about her, while the "real" Pinkie Pie can only be described as a set of every possible image of her there is, making her less of a "lifeform" and more of a relative to infinity itself. This is because everyone, even the writers of the show itself, have slightly (or extremely (Cupcakes)) different ideas of what makes Pinkie Pie herself. As there cannot be two people who think the same about her there can be no opinion that is more or less wrong than every other. Sure, there are opinions that have a bigger impact on her depiction in the show and therefor on our opinion, but those are still not worth more (or less) than ours. And because of this it is not only wrong in this case but impossible that she could ever be in my head as my head can only take a finite quantity of knowlegde while she herself is an possibly infinite amount of impressions and opinions.
Now if your head does not smoke yet you are clearly smarter than most people I know.
It is up to you to call or not to call a mental construct in your brain Pinkie Pie. My point is that there is no physical mare named Pinkie Pie which we can consider real. The only thing a person could have is a mental construct in the brain based on the information from the show, fan fiction and other sources. We can name it Pinkie, because writers of the show scripts and some other people would do so. Or we can do like you suggest, use the name only for the whole body of knowledge about Pinkie Pie.
P.S. And there is one thing we shouldn't do: dispute definitions.
Yeah only mathematicians have a reason to dispute about definitions. But I ask you one thing: Aren't the show, our minds and everything both contain real? If something is not real, wouldn't that mean that it does not exist? This is the problem with the very loose definition of reality. I tend to say that everything that can be imagined can potentially be considered real. The opposite would mean that you can only be sure about your own reality as you depend on your senses and of course your brain. The world of somebody with hallucinations is not less real to him than our world is to us. But at the same time it is "not real" by our standards. The problem I'm having is, where is the line between "real" and "not real"?
A possible solution of this issue is to accept that something can be real for one person and not real for another. But it is not the only way.
I know good definition of delusions, as written in "Diagnostic and Statistical Manual of Mental Disorders" (DSM): "A false belief based on incorrect inference about external reality that is firmly sustained despite what almost everyone else believes and despite what constitutes incontrovertible and obvious proof or evidence to the contrary." As an opposite of delusions you can find what the real things are. I like this approach because it is very practical.
Still a very problematic definition if you ask me. This would mean that Galileo Gelileis ideas would've been delusions by the standards of his time. Today we know, he was right. But that's as good as we can get I guess.
Galileo confirmed Copernicus' prediction about full set of Venus phases, based on the the heliocentric model. So he had proofs and his opponents should be considered delusional because they ignored obvious facts.
This is my brain And I live in it. It's made of love and bad song lyrics. It's tucked away behind my eyes Where all my screwed up thoughts can hide 'Cause god forbid I hurt somebody. -- Tim Minchin, 'Not Perfect'