The building's PLUMBING.
The Big Bang Theory Season 4, Episode 18
I'm quite familiar
with PLUMBING.
The Big Bang Theory Season 7, Episode 2
...but it's nice to know
everything's okay with your PLUMBING.
The Big Bang Theory Season 4, Episode 18
...suggest that Leonard is humorously
mocking your efforts in space PLUMBING.
The Big Bang Theory Season 2, Episode 22
and not pick up a few things
about PLUMBING.
The Big Bang Theory Season 10, Episode 4