![Penny, this is Sheldon's twin sister.
Missy, this is our neighbor Penny.
Penny, this is Sheldon's twin sister.
Missy, this is our neighbor Penny.](data:image/png;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=)
Penny, this is Sheldon's TWIN sister.
Missy, this is our neighbor Penny.
The Big Bang Theory Season 1, Episode 15
![](data:image/png;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=)
"Made up my mind to date both of them
by pretending to be TWIN brothers."
The Big Bang Theory Season 9, Episode 14
![but when they're twin primes,
but when they're twin primes,](data:image/png;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=)
but when they're TWIN primes,
The Big Bang Theory Season 9, Episode 12
![...and his five twin brothers,
you are wasting your time.
...and his five twin brothers,
you are wasting your time.](data:image/png;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=)
...and his five TWIN brothers,
you are wasting your time.
The Big Bang Theory Season 1, Episode 16
![...since I beat out my twin sister
for the ...since I beat out my twin sister
for the](data:image/png;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=)
...since I beat out my TWIN sister
for the "Did It On The Potty" trophy.
The Big Bang Theory Season 8, Episode 23