
"The CHALLENGING
climate of Scandinavia
The Big Bang Theory Season 12, Episode 23

It really doesn't matter
as long as it's CHALLENGING.
The Big Bang Theory Season 10, Episode 22

Being your girlfriend is so CHALLENGING.
The Big Bang Theory Season 8, Episode 24

Intimacy in any form
has been CHALLENGING for me,
The Big Bang Theory Season 9, Episode 11

...indicating he's CHALLENGING
the ruling on the field.
The Big Bang Theory Season 3, Episode 6