When I was at school there was a newsagent around the corner that sold real Mexican Jumping Beans, in little tubes containing about five each. Not the little plastic lozenge-shape toys with ball-bearings giving them momentum, but the real things (see Wikipedia article). I couldn’t believe what I was seeing when one of them would jump. It seems like they only had them around in the shop for about two weeks, and then they were gone. Years ago I went back to that shop to ask them about it, but the person there didn’t know anything about them.
If you put one onto your hand, the warmth from your hand would make the moth larva that lives inside twitch to try to move the bean somewhere cooler.
Anyway, we’d been talking about toys we remember from when we were young, and those beans were pretty high up my list.