![I challenge you to find a single reference
to Kryptonian skin cells.
I challenge you to find a single reference
to Kryptonian skin cells.](https://content2.mcqstudy.com/ss/tbbt-1-2-00:03:34.046.jpeg)
I CHALLENGE you to find a single reference
to Kryptonian skin cells.
The Big Bang Theory Season 1, Episode 2
![Go old-school,
challenge Stuart to a fight.
Go old-school,
challenge Stuart to a fight.](https://content2.mcqstudy.com/ss/tbbt-5-10-00:12:33.003.jpeg)
Go old-school,
CHALLENGE Stuart to a fight.
The Big Bang Theory Season 5, Episode 10
![I always got stuck on
the first challenge--
I always got stuck on
the first challenge--](https://content2.mcqstudy.com/ss/tbbt-7-3-00:01:07.772.jpeg)
I always got stuck on
the first CHALLENGE--
The Big Bang Theory Season 7, Episode 3
![Surely there are others out there
who still dare to challenge my reign.
Surely there are others out there
who still dare to challenge my reign.](https://content2.mcqstudy.com/ss/got-42-00:43:59.250.jpeg)
Surely there are others out there
who still dare to CHALLENGE my reign.
Game of Thrones Season 4, Episode 2
![Really give ourselves a challenge.
Really give ourselves a challenge.](https://content2.mcqstudy.com/ss/tbbt-8-3-00:14:16.891.jpeg)
Really give ourselves a CHALLENGE.
The Big Bang Theory Season 8, Episode 3