This is a great movie because it has scene after scene of great marijuana related slapstick comedy.
It kinda keeps a loose plot going based upon Cheech and Chong first meeting up and playing in a band together. With the finale being the punk rock battle of the bands at the end.
Here is a classic from the movie:
"Hey how am I driving, man?"
"I think we're parked."
and of course:
"Hey, hey don't take those, man."
"I almost gave you the wrong shit, man."
"Hey, man, I already took 'em, man."