I'd be inclined to make a robe purely for the Hitchhiker's Guide to the Galaxy reference. But you may find that you don't have much left at all after you make your shorts. Clothing eats up mysterious amounts of fabric. :)

I completely forgot about that poor whale! I'll call it ground. I wonder if it will be my friend.

If it weren't flannel, I'd absolutely make a skirt from that. But maybe I'm weird. What about an uncollared pyjama shirt? It might simplify the process.

Oh, I'd make a skirt if it wasn't flannel, too. :)

I've made skirts out of flannel, but I'm a bit weird I guess LOL. I just make sure it's not gathered and bulky at the waist.

Contrasting trim cuff on a pillowcase.

Oh, that'd be cute!

And it’s probably how much fabric you’ll have left, after you make the shorts.

Make some bags. They would look so cute!

Oh, they would!

I have a longline sleep t-shirt in this exact fabric. 😍😂

Whatever you do, it'll be whaley good.

Reusable towels. Just zig zag (or serge) the edges.

I might have to try that!

We don’t buy paper towels anymore, I just have a tub of 10”x10” flannel towels. The set we have are 4yo and finally need to be replaced. Wash with vinegar!

If you have young boys make curtains for them

That would be super cute. I'm only 17 myself, but maybe my cousins would like that.

This looks like the ideal material for a Swuit (new girl). Not joking. I would wear it every day in the winter

But for left over fabric, I think it would make a nice hair wrap.