And you get cancer

Yellowcake, sponge... lemon flavoured sponge cake?

It looks like the underside of a microfiber towel

That’s why they have it in a frying pan

I'm talking about thermally cooling it down. If you put it in a freezer it will cool down, but the nuclear process will not change speed.

this is a commonly repeated ~~falsehood~~ obvious joke

And, if I have to explain the joke: it's just E=mc² (the Einstein thing ... well, the Einstein's thing's approximation), the energy (E) is the same for all mass (m) since the c is a constant.
You get the same 21 billon kcal from 1g of apples as from 1g of plutonium.
And since it's usually well known humans do not devour mass into pure energy that might trigger ppls sense of humour.
(Additionally the idea of eating metal to seek nutrition might be funny, but we do need some metals \m/.)

Also "potential energy" phrasing is weird in that context.

There are 2 different definitions of calorie.
This "fun fact" mixes up the two definitions

It's not even two definitions, the kcal is absolutely the same, it's just used to measure two different things (mass energy vs the sum of what an average human can extract via chemical processes). I see you def understand that, but it's not a different definition of a calorie (in the same way as length vs width of an object isn't a different definition of a metre).

Hey, sexy bone-marrow pelvis, shake them atomic gains!

(OK, but like, if I produced synthetic plutonium I would make the box look like a chocolate box. Those workers & engineers deserve to have a fun work environment, engage in some shenanigans, make an oopsie from time to time.)