I found this site with thousand of conversation starter questions of all types. These could be saved in a text file and used as the basis for an Auto-Idle plugin by letting Hal randomly choose one of the questions when conversation stalls.
http://www.saviodsilva.org/Scroll to the bottom of the page to find questions in many different categories. Here is a sampling of the "Silly questions" ...
Why can't women put on mascara with their mouth closed?
Why doesn't glue stick to the inside of the bottle?
Why don't you ever see the headline Psychic Wins Lottery?
Why is abbreviated such a long word?
Why is a boxing ring square?
Why is it considered necessary to nail down the lid of a coffin?
Why is it that doctors call what they do practice?
Why is it that rain drops but snow falls?
Why is it that to stop Windows 98, you have to click on Start?
Why is it that when you're driving and looking for an address, you turn down the volume on the radio?
Why is lemon juice made with artificial flavor and dishwashing liquid made with real lemons?
Why is the man who invests all your money called a broker?
Why is the third hand on the watch called a second hand?
Why is the time of day with the slowest traffic called rush hour?
Have fun
Davy