
...suggest that Leonard is humorously
mocking your efforts in space PLUMBING.
The Big Bang Theory Season 2, Episode 22

I'm quite familiar
with PLUMBING.
The Big Bang Theory Season 7, Episode 2

The building's PLUMBING.
The Big Bang Theory Season 4, Episode 18

...but it's nice to know
everything's okay with your PLUMBING.
The Big Bang Theory Season 4, Episode 18

and not pick up a few things
about PLUMBING.
The Big Bang Theory Season 10, Episode 4