Careful, Leonard. Liquid nitrogen,
320 degrees below zero.
The Big Bang Theory Season 1, Episode 5
You see, instead of
using LIQUID helium...
The Big Bang Theory Season 11, Episode 8
I'm not seeing anyone
using LIQUID helium vortices like this.
The Big Bang Theory Season 9, Episode 16
It's like a waterfall
of LIQUID gold.
The Big Bang Theory Season 5, Episode 1
The correct answer is, "When covered by
LIQUID sufficient to reduce the coefficient...
The Big Bang Theory Season 2, Episode 5