
Point is, Sheldon, the legal PRINCIPLE...
The Big Bang Theory Season 4, Episode 21

The holographic PRINCIPLE suggests...
The Big Bang Theory Season 6, Episode 5

...and I avoid contact with other people
on general PRINCIPLE.
The Big Bang Theory Season 3, Episode 15

...the PRINCIPLE that a physical system exists
partially in all its possible states at once.
The Big Bang Theory Season 6, Episode 19

That's sort of like
the uncertainly PRINCIPLE.
The Big Bang Theory Season 4, Episode 20