"Made up my mind to date both of them
by pretending to be TWIN brothers."
The Big Bang Theory Season 9, Episode 14
I already shared a uterus
with my TWIN sister.
The Big Bang Theory Season 12, Episode 19
but when they're TWIN primes,
The Big Bang Theory Season 9, Episode 12
Penny, this is Sheldon's TWIN sister.
Missy, this is our neighbor Penny.
The Big Bang Theory Season 1, Episode 15