
I know what a CHALLENGING man he could be,
The Big Bang Theory Season 9, Episode 14

- Just as CHALLENGING as you?
- Yeah...
The Big Bang Theory Season 10, Episode 5

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

Oh, we'll make the puzzles
extremely CHALLENGING
The Big Bang Theory Season 9, Episode 8

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