Unless they're German,
The Big Bang Theory Season 7, Episode 12
You know,
the German philosopher,
The Big Bang Theory Season 5, Episode 7
Now, in German.
The Big Bang Theory Season 10, Episode 20
No, I don't know German.
The Big Bang Theory Season 2, Episode 3
Like reenacting the ancient German practice
of trial by combat.
The Big Bang Theory Season 8, Episode 19