You see, instead of
using LIQUID helium...
The Big Bang Theory Season 11, Episode 8
They make up a non-Newtonian fluid
which is LIQUID...
The Big Bang Theory Season 2, Episode 3
Floating in a warm pool
of LIQUID
The Big Bang Theory Season 12, Episode 19
The correct answer is, "When covered by
LIQUID sufficient to reduce the coefficient...
The Big Bang Theory Season 2, Episode 5
The world's most boring LIQUID
and the world's most boring vegetable,
The Big Bang Theory Season 10, Episode 13