Recreate the Pet Rock Fad
Back in 1975, pet rocks were a fad - for about 6 months. Today you can bring them back by adopting one.
Pet rocks have an amazingly long lifespan. If you look around a bit, you might be able to find one of the original pet rocks. About 1.5 million of them were sold in those 6 months.
If you can't find an original, you probably can get one of their descendants. Check your back yard. By now they've likely migrated just about everywhere.
If you don't want a wild rock, I see that you can buy domesticated rocks on eBay. It looks like they come in a box, complete with nest, leash, and proper care manual, much like the originals did many years ago.
Apparently people still pay about $15 for them.
We have our own pet rock in the front yard. It's really more like a boulder. I was told it had character. Still not sure that I see that. Mostly it's just getting smaller.
Some years it tries to grow a tree from one of its fissures. I hope it succeeds sometime.