
When I broke up with Penny,
I got back into my CELLO...
The Big Bang Theory Season 4, Episode 3

How do you meet girls playing the CELLO?
The Big Bang Theory Season 6, Episode 18

Leonard, I didn't know
you played the CELLO.
The Big Bang Theory Season 1, Episode 5

...building computers
or practicing your CELLO...
The Big Bang Theory Season 8, Episode 22

This one birthday,
I came home from my CELLO lesson...
The Big Bang Theory Season 1, Episode 16