An emotion you feel when you are nostalgic for a time you were never alive in.
It is a proper subclass of nostalgia.
Protonostalgia is like when a chick is nostalgic for the time of pirates! Or, when a dude misses being a 16th century courtesan. It also happens when folks spend a lot of time wishing they could be Shakespeare's pal!
"Do you miss being a pirate? I miss being a pirate!"
Pornostalgia evidenced when watching porn: (i) "Where's the plumber/pizza delivery boy?"; (ii) "Where are the pubes?"; (iii) "Those ain't real"; (iv) "The production values of this movie really are first class"; (v) "Do you remember AIDS?".
A feeling one gets of being nostalgic for a period of time or place they had never been. Coined by Ryan Norths Dinosaur Comics.
"Aww, man, I have really big feeling of protonostalgia today. I wish I could have been a caveman. I wish I had a club and killed Sabre-tooth tigers. Wouldn't that be sweet?"
Bro: Man, I'm having such a good time right now, I don't wanna leave this. This is gonna be a memory one day.
You: Hey man, no prenostalgia. Live in the moment.