Not Bionicle parts, but Lego parts:
Anyone remember a certain type of Lego racer, the type that had a little car with an ejector seat and a slammer launcher? Well, I had all of those except for the one that had the glow-in-the-dark pilot. My younger brother really liked them, so one day he took them to a grocery store when the nanny that we used to have took him there. He kept on dropping the pilots, and the nanny kept on having to pick them up. The nanny told him that if he dropped them again, she wouldn't pick them up. So of course, he dropped them again, and she didn't pick them up, and I never saw them again.
This is why I am missing some of the coolest of those racers.