Yensid wrote:
Here's a strange one: brine shrimp. You can buy these little eggs, and put them in salt water. The next day, there are these tiny little shrimp swimming around. They used to sell them as "sea monkeys".
They still do, I believe! I had a colony of them a few years ago. It was fun to watch them squirt about. Also fascinating how their eggs can remain in a suspended state and then be re-activated with water and feeding. As they grew larger, their number decreased until I had about five that were about the size of my pinky finger nail.
Then my cat knocked them over and I had dried sea monkeys on my floor
sadly they were too small to fry up.
Other things that have entertained me:
golfing in public at night (do not do this if you live in a city with a police force with no sense of humor)
setting up rope swings from streetlamps
city = guerrilla jungle gym
art from recycled / found objects
Also, a good friend who is in his 40s (and probably neurotypical but very atypical and interesting) builds ant farms. Apparently you can order ants online.
Speaking of insects, I used to put [url=http://www.youtube.com/watch?v=-2LPHeSAk9Q]bees on a leash[/url when I was a kid. I thought I had this idea all on my own but turns out others have also decided to exact revenge on the little buggers. Unlike dude in this video, I used a piece of meat in a plastic container and then put the lid on once I had attracted a bee. Do not freeze it for more than a few seconds or else it will die! Animal cruelty not included (you can let the bee go once you are through with it and it will likely chew its way out of the leash).