I work with a guy in his 60s who NEVER shuts up. He talks, and talks, and talks, and talks. The only time he’s not talking is when he’s in his office, and alone.
His office is right next to mine. I *hate *it when his phone rings, because it means he will be gabbing for the next 20 minutes, and my officemate and I have to suffer through it. 
For comic relief, I play the first 20 seconds of this song whenever he’s talking non-stop in his office. It always brings a chuckle to my coworker and me.
I have a good friend who is a Maynard, and I have used the following with him:
[ol]
[li]Just the executive summary, please[/li][li](on the telephone) Push a button to “beep” him[/li][li]I don’t recall my asking[/li][/ol]
However, one of phungal’s friends’ husbands is a Maynard, and I was tasked with the job of “Social Assassin” and say something, as we were all tired of being stranded on “Maynard Island”. Based on my experience, saying “Yeah, I’m REAL interested in that, could you start another topic and tell me MORE?” is not effective. In the end, I hurt his feelings, and didn’t change him one bit.
The is an excellent option.
start calling the person Cliff as you address them.
This sounds like it should be a movie quote, like maybe something from The Princess Bride.
“we are men of interesting hobbies. Being boring does not become us.”
I don’t have a Maynard, but that made me laugh.