One-liners...I Want 'em

I'm not a particularly jealous person, but I do covet the ability some have to think of witty, clever shots, short but with lots of punch. Here are just a few.
Calvin Coolidge was asked after church one day what the minister's sermon was about. "Sin," the notoriously terse Cal replied. "And what did he say about it?" the reporter asked.
"He's against it."
Winston Churchill was apparently irritating, at least on one occasion, and a woman said to him, "Mr. Churchill, if you were my husband, I would put poison in your tea."
To which Churchill replied, "Madam, if I were your husband, I would drink it."
And a Canadian comedian I saw just last night tells of his entry in Australia. The customs guy asked, "Do you have a criminal record, sir?"
And his reply: "I didn't think we needed one to get in here anymore."
Now why can't I think of such clever replies when the conversation becomes inane or proscribed or too personal? I am a victim of houritis, the condition where that witty remark occurs to me when it's too late, and the moment for rapier wit is lost forever. It doesn't do to chase folks down and tell them, "You know, when you said what you said, I wanted to reply... "
Give it up, and hope to do better the next time.
I did actually get the Golden Chance once when a man asked me (English teacher, remember) if I liked Kipling.
Should I? Did I dare? I did.
I replied, "I don't know. I've never kippled."