I think one of the best things about childhood is the newness of everything. Almost everything has a steep learning curve, but children for the most part have no conception of how unlikely swimming or learning a language or whatever is, because (I suppose) their whole lives are a stream of new, improbable things which prove attainable.
What I am trying to say is I have completely spent my fun budget and have to start budgeting again, and i don't know whether to budget for a unicycle or a slackline.
Yes Unicycle: I have never tried it and don't know anyone who has one, so it is a totally new skill. I can probably pull it out and take it around the immediate neighborhood quite easily compared to setting up a slackline. Also, if I get a touring one (oh, they are expensive) perhaps I can throw away my terrible bicycle that is so terrible that it goes down hills more slowly than other bikes. One time someone cut one of the brakes, but it still has one that works so I use it as-is. One time someone peeled off the cushion part of the seat, but there is still a plastic triangle so I use it as-is. It is such a terrible bicycle that I can't ride hands-free on it but I can on Dad's bike with suicide gears and meant for someone 6 inches taller. It is so bad that someone once stole the bike crate* but not the wheels or anything. Also, when I once left it unlocked in downtown Oakland it was not stolen when I got back 5 hours later. And when I got back from Christmas break having left it at the bus station I found that the lock's cable had been halfway cut, but not all the way. I still use that bike lock- I figure it has already proven it's effective.**.
Against Unicycle: What if I am terrible at it and I break my arms? I do not like getting hurt. And a touring unicycle, which is what I really want, is $600.
Slackline: Slacklines are really portable, and I could use it at the condo and at Willow House. Also, I am much closer to being able to slackline than to being able to ride a unicycle. And, it does not hurt much to fall off. And they are 1/3 as expensive as a beginner unicycle.
Against Slackline: There is a slackline club at school that I could go to if it wasn't raining and if I wasn't afraid of ripping out my navel ring***, so I don't need to own one in order to learn it. The set up would be time consuming.
*Just to be really clear, it was not a nice crate. It was a beat up black milk crate with one corner gone from where a side view mirror hit me one night.
**I think it would be unethical to leave it unlocked in case a child steals it and is killed when they assume the brakes brake.
***I am not sure why I care- I learned to eat with my mouth ages ago and I am not using my belly button for anything at all anymore. I am not even keeping it intact.