
Penny was the teacher.
When the light turned YELLOW...
The Big Bang Theory Season 3, Episode 16

What does red and YELLOW mean?
The Big Bang Theory Season 8, Episode 22

Under the sink. Yellow Tupperware bowl.
The Big Bang Theory Season 1, Episode 11

No red and YELLOW,
no red and YELLOW.
The Big Bang Theory Season 8, Episode 22

Yellow. Go ahead.
The Big Bang Theory Season 4, Episode 22