Here's another unfinished sentence I wrote and the responses it elicited in the early '90s:
The 158th bizarre quirk about human nature that leaves me in a puzzled daze is...
...the ability to rationalize anything, most often used to justify the continuation of behavior that is destructive to self and others. Example: Even a monster like Hitler thought he was doing a good job. This trait obviously isn't conducive to the perpetuation of our genome, now, is it? (Randy R.)
...their tendency to slip a huge thought into a superficial conversation. (Karen B.)
...the inability of people to do the easy thing when a harder thing is available. (Chip C.)
...people who couldn't give a @#&* about the rest of the world assume they are being watched with passionate interest. (Michael M.)
...no one recognizes or likes their own voice upon hearing a recording of it. (Sean B.)
...Why is black licorice an acquired taste? Is red licorice so different? (Liz F.)
...human kindness, in the midst of telemarketers and a shifting economy. (Paul I.)