I bought an N-gauge LOCOMOTIVE.
The Big Bang Theory Season 5, Episode 3
"You are running the LOCOMOTIVE."
(GASPS)
The Big Bang Theory Season 10, Episode 15
If you knocked I couldn't hear you.
I'm welding this LOCOMOTIVE engine.
The Big Bang Theory Season 10, Episode 15
U.S. LOCOMOTIVE
ever built?
The Big Bang Theory Season 7, Episode 15