
...and did so
using a stern facial EXPRESSION.
The Big Bang Theory Season 4, Episode 24

This calls for an
EXPRESSION of gratitude.
The Big Bang Theory Season 5, Episode 20

I thought it was an EXPRESSION
of passion,
The Big Bang Theory Season 5, Episode 14

What exactly does that EXPRESSION mean,
"friends with benefits"?
The Big Bang Theory Season 2, Episode 21

It led to an interesting EXPRESSION
in our house:
The Big Bang Theory Season 2, Episode 9