
- Helium.
- Yes.
The Big Bang Theory Season 9, Episode 23

You and Sheldon already came up
with your superfluid HELIUM model.
The Big Bang Theory Season 9, Episode 16

Not quite accurate.
The Macy's balloons are filled with HELIUM...
The Big Bang Theory Season 4, Episode 24

Forget HELIUM. The real superfluid
is the fruit punch in this mug.
The Big Bang Theory Season 9, Episode 16

Helium has
an atomic number of two.
The Big Bang Theory Season 7, Episode 3