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