Someone who shines extra sparkly. Particularly on the day of their birth with another human who also sparkles brightly on the same day.
Not to be confused with: "sparkle adjacents", "shiny duplicates" or "firework friends".
"That Carly Rae Jepsen is twinkle twins with that dashing human resources manager I know." "You mean they share the same birthday Ted?" "Yes Bob." "Just say that next time...instead of sounding like a f#%$n idiot." "Dually noted Ted - dually noted."
To Twinkle Twin: Ignore Ted and proceed rejoicing in the Sparkle of shared birthdays.