Jon Klassen’s We Found a Hat is fantastic. The end isn’t as ambiguous as his last book (written by Mac Barnett), Sam & Dave Dig a Hole (speculation got a little crazy on that one), but maybe there is some room from interpretation. Here’s my theory:

The hat the turtles find actually belonged to The Man in the Yellow Hat – you know, the dude from Curious George – who met his demise while on some ill-fated adventure in the desert. Maybe an all-out effort to save George’s kite. 

I mean, look at The Man in the Yellow Hat’s hat:

The Man in the Yellow Hat, in happier times.

Now look at the We Found a Hat hat:

Same hat, am I right? Just faded to white from the relentless desert sun.

Unbeknownst to the turtles, they have been chosen to shepherd The Man in the Yellow Hat’s spirit – which is contained in the object that most represents his earthly form – his hat – into the afterlife. This, of course, can only be done in a dream state.

But there’s a problem.

You see, taking ownership of a spirit-containing hat can release the spirit prematurely, forcing it to haunt the earth for all eternity. So things nearly fall apart when the turtle considers taking the hat as his partner falls asleep on the rock.

Thankfully, the turtle thinks better of it and joins his pal on the rock, where they fell asleep and everything goes according to the master plan.

So what happens after the book ends? Well, if I were to speculate, I’d say the physical hat will be gone when the turtles arise (replaced by George’s kite), and they will have no recollection of the waking events of the previous day – but full recollection of their spiritual dream-journey.

Or, I don’t know, something like that.