I know what you’re thinking.
Free box! Free plastic box! Free plastic box I can slide under my bed!
I have to bring you back down to Earth. Because this box fits under your bed, it has to be shallow. I don’t mean “Kim Kardashian shopping for wedding gowns while pregnant” shallow. I mean it isn’t very tall.
So, no, you can’t fit a body in there. I mean, you can try. You can use a radial arm saw to thin out the thicker parts of their bodies (torso and skull), but it’s a big, messy job. Also, this box has hinges on the lid, so liquids and odors will leak out through the cracks. If anyone is with you on top of the bed, they’ll probably notice, and you’ll need to get another box for your collection.
In the end, you’d be better off if you got a different tub. This one is better for your other hobbyist materials: knives, axes, piano wire, dismembered hands, or your copy of Atlas Shrugged (although that last one is going to be a tight fit).
If you have a need to keep any of those under your bed, this box is for you.