
was an obvious REFERENCE
The Big Bang Theory Season 7, Episode 3

I'm surprised you know that REFERENCE.
The Big Bang Theory Season 8, Episode 19

What?
You're familiar with the REFERENCE?
The Big Bang Theory Season 10, Episode 7

I challenge you to find a single REFERENCE
to Kryptonian skin cells.
The Big Bang Theory Season 1, Episode 2

What REFERENCE?
The Big Bang Theory Season 8, Episode 19