Cheech was Don Johnson's partner on the series and Tommy Chong was playing a mob acountant, or some such, that was cooperating in a bust. Cheech and Chong went to a "Medical Marijuana Club" smoking room to bust one of the suspects, who was stoned out of his gourd. This resulted in one of my favorite lines on TV ever.
Cheech flashed his badge at the suspect and said something to the effect:
"step away from the bong and keep your hands where I can see them."
And yes, it was a classic episode.
RI got a good laugh when the Chong character asked the Marin character what his current drug of choice was and he replied, Rogaine.