I have a close friend who was in the habit of getting into arguments with an older relative, who holds a number of provocative and politically incorrect opinions. Something like Archie Bunker without the pleasant personality.
My friend argues with him. It is hopeless to change his mind, he knows what he knows, and the discussion rapidly turns into a rancorous argument.
I have pointed out to her that she is arguing with a gentlemen who knows what he knows and cannot conceive that there is another legitimate viewpoint. She has no chance of influencing his opinion. And to argue with him also reflects badly on her - Only a fool would argue with a grapefruit. If you argue with someone dumber than a grapefruit, well, then you are also dumber than a grapefruit.
So when the argument starts I just work the term grapefruit into the conversation. This makes her laugh and she see the futility of the conflict. He can't hear well and so does not hear the word grapefruit.
Smooths things over and we avoid having a tedious and disruptive hassle.
A grapefruit does not have to be stupid. In fact, there are a number of very smart folks who are so angry and obsessed about someone or something they don't like that they become grapefruits, albeit smart ones. They know what they know, they cannot accept anyone who has a different opinion, and often become hostile and abusive. This often manifests itself in hatred of political figures, for example hatred of Presidents Reagan, Bush, Clinton, Bush, and Obama.
It is not a particular vice of either liberals or conservatives.Grapefruititis can strike anyone of any age and any political persuasion. It perhaps gets worse with age, with hardening of the arteries.
It is easy to see others who are grapefruits. It is hard to see ourselves.
Now everyone should want to avoid being a grapefruit. And it is hard to see if you are becoming a grapefruit. Like alcoholism, many people gradually slip into grapefruititis without realizing.
Some danger signs that you might becoming a grapefruit:
You know all the answers.
You call other people stupid or liars.
You are often outraged when you read things you don't agree with.
You constantly demean elected officials, not with well reasoned arguments, but with name calling.