The joke for which I will remember 'Cannon'...
... is the joke about him wanting to eat a sandwich many times throughout the episode, but each time he wants to take a bite, the phone rings. Frustration all over. In the second half of the episode, when Cannon wants to take a bite, he remembers his bad luck just in time and takes a good look at the phone first to make sure it does not ring. Reassured, he decides to finally take that bite. And exactly at that moment, the phone starts to ring...
Such a simple joke. But it was perfect timing, and perfectly executed. I still remember it after 35 years, here at the other side of the world (Amsterdam). So it must have had some quality.