What's your weird food substitution story?

I'm playing around with cooking ingredients after the crunch-time craziness at work (and some resulting stress gut irritation). Which means I'm trawling around the internet looking for and finding substitutes for butter, dairy, and fruits that aren't in the FODMAP list, which has in turn lead to my discovery that coconut oil can be substituted for butter in many cooking situations.

Yup, looks like a strawberry-banana crisp to me.

Yes, I didn't know that. I do now, and have begun my first experiment in using it as part of a strawberry-banana crisp topping. It was a pretty simple recipe, and seems to have the same texture of butter, so I'm hopeful it'll turn out well. Will report the findings after a tasting.

I'm sure everyone's had to substitute things in recipes before, whether due to food allergies, special diets, or just running out. What's the best and/or weirdest substitution you've used that worked?

And more entertainingly, ever tried anything that didn't?