
...the invitation
to join the Arctic expedition.
The Big Bang Theory Season 2, Episode 23

I don't know what Arctic expedition
you were on...
The Big Bang Theory Season 3, Episode 1

I'm going to the Arctic Circle with
Leonard, Wolowitz and Koothrappali.
The Big Bang Theory Season 3, Episode 1

You know, last time, I was able to book
a cruise to the Arctic to see a solar eclipse.
The Big Bang Theory Season 1, Episode 5

...on the NSF expedition
to the Arctic Circle.
The Big Bang Theory Season 2, Episode 23