Well, the reason nopony recognizes Twi s’ costumes, is because she is always dressed as (semi)historical figures. Not as something that someone would be dressed at the My Little Pony version of Halloween. And also because they are not that recognizable The only ponies really this well-versed could be counted on two hands: you, Luna, Celestia… maybe Cadence.. Doctor Whooves… Mayor Mare, Octavia? Maybe Rarity? Really, i cannot imagine anypony else remembering that much of history. Cheerilee just teaches Modern Equestrian language to 7-year-olds, so she does not have to be well-versed. And notice that only three of these ponies i’ve mentioned live in Ponyville, excluding you. And propably Mayor Mare is just versed in law and justice either, so she does not know history that is not related to Ponyville itself. Rarity is the one that you commission for the costumes, and before you came in Ponyville she would have never trought of someone dressing as Coperneighcus. Then there is Doctor Whooves, the only other pony in Equestria to be as well-wersed as you except for the above ponies and some of the most uppity Canterlot nerds.
 
(Dressing as an historical figure seems like something my 32-year-old teacher would do.)

Awesome, you used the phrasing! I feel all special and stuff.

Dragonception!

Twilight is best beet.

lol at the tiny glasses

@sargesprinkles
 
The joke is that he thinks he’s doing something different when he’s still completely missing the point.
 
It depends on the canon gag, but I don’t think it’s “ripping the joke straight from the show”.

The Spike part is that he’s dense.
 
So dense that he doesn’t get the joke every year just like Twilight.

Coperneighcus?
 
Nice pun.

i was more pointing out the spike costume.  
i get the twilight part

@sargesprinkles
 
The joke isn’t so much that nobody gets her costume, it’s that this happens to Twilight every year. :E

older spike HNGG

no offence, but isn’t this ripping the joke straight from the show?

Luna’s carriage in fourth panel.

Luna chariot in the background of panel 4

Kein. Tag your stuff right. Please.

…Twilight says funny words.

Congrats on getting your joke canonized, Spiritus Arcane.