If you’re a parent, or have been a parent, then Pippin Barr’s Jostle Parent will be a familiar experience. If you—like me—haven’t had kids of your own yet, then this will only put you off the idea completely. It’s what Barr rightly determines a more tragic riff on the concept behind Octodad: Dadliest Catch—”you’re a similarly limited person with similarly limited communication skills, but you still have to do this important job of protecting your family,” he writes. Here’s the set-up: you’re on your own, you have three kids to look after, and all you can do is jostle. Yes,…