
...through WHICH they trudged.
The Big Bang Theory Season 3, Episode 14

Which is fine,
but it's nice to mix it up
The Big Bang Theory Season 7, Episode 1

Speaking of WHICH, ahem,
Breaking Bad Season 4, Episode 8

Wait, I don't...
Which part?
The Big Bang Theory Season 5, Episode 7

Okay, I'm confused,
WHICH one is Mr. Robot?
The Big Bang Theory Season 10, Episode 5