Humanoid Universe Theory: Humanoid Pinkie Pie mentioned she knew of a girl who looks just like Twilight who lived in the city, which means that Flash Sentry never actually met the Twilight Sparkle of his world, in the movie at least. So, assuming that Humanoid World's Twilight Sparkle never was in Canterlot High (since no one recognised our Twilight during her time there), technically she never knew Flash Sentry.
Therefore, who's the creep that just bought her chocolates?
(No, Cadance and Shining Armor are not high school students, just so it's clear. I wrote a less funny short story
in regards to this.)
An allusion to I'm Watching You, Bub.
"My Little Pony: Friendship is Magic", "Equestria Girls" & Original Characters © Hasbro