
If you knocked I couldn't hear you.
I'm welding this LOCOMOTIVE engine.
The Big Bang Theory Season 10, Episode 15

If you listen carefully when
the LOCOMOTIVE disconnects,
The Big Bang Theory Season 7, Episode 15

I hear LOCOMOTIVE smoke
is the second leading cause...
The Big Bang Theory Season 8, Episode 22

I bought an N-gauge LOCOMOTIVE.
The Big Bang Theory Season 5, Episode 3