Ok, confession time given that a client just sent me a picture of my soap, decorated and looking dangerously edible.
I messed around quite a while a few years ago with making soap from biodiesel byproducts. (Mostly glycerine is left over when you make biodiesel). It worked really well as soap, but was hard to sell; mostly because the texture always stayed soft. So I mucked around with making liquid biodiesel soap as well. (I can say if you do this, it's one of the best grease-stripping agents on the planet, seriously. Just hard to ship or transport.)
Because of the ... stuff....left in it, and so on, this liquid soap was dark brown. And because it was experimental stage stuff, I naturally hadn't bought containers or anything for it. When I was done cooking the stuff, I looked around the kitchen for something to pour it into--fished in the recycling, and grabbed out a 2-liter plastic Coke bottle.
And forgot to label it.
And my husband grabbed it for a swig when he got home from work before I could warn him.
I still feel bad about this.