"Helium."
The Big Bang Theory Season 2, Episode 5
Not quite accurate.
The Macy's balloons are filled with HELIUM...
The Big Bang Theory Season 4, Episode 24
You and Sheldon already came up
with your superfluid HELIUM model.
The Big Bang Theory Season 9, Episode 16
I'm not seeing anyone
using liquid HELIUM vortices like this.
The Big Bang Theory Season 9, Episode 16
One time my brothers
made me breathe HELIUM.
The Big Bang Theory Season 12, Episode 6