I saw last Sunday on METV the episode where Reverend Jim takes his driver's test to become a cabbie. When he takes his test, he asks Bobby "What does a yellow light mean?' Bobby says "slow down." Then Jim says " what does a yellow light mean? It was a very funny exchange. Anyone remember this scene?

Yeah. That's probably the most famous Taxi scene that there is.

gosh yes!

good times !

in the book "Hailing TAXI" they say how that entire exchange was ad-libbed or something.