Indeed, one of the memorable stories from https://www.amazon.com/Ignition-Informal-History-Liquid-Prop... was when the author wrote a joke paper analyzing the optimal amount of mercury (!) to mix into rocket fuel for maximal thrust. It takes away from the power, but since mercury is heavy it slows the exhaust, and therefore can increase thrust.

To the author's surprise, the general evaluating the crazy ideas that the lab came up with failed to recognize that it was meant as a joke, and ordered that it actually be tested. So some unfortunate test site had to actually set up the test, and verify the theory.

Luckily the military came to their senses about then and never actually built real rockets using the principle.

(For those who are confused, mercury may be heavy, but is a nasty contaminant. Organic compounds including mercury have a disturbing tendency to be neural toxins. See https://en.wikipedia.org/wiki/Karen_Wetterhahn for a famous example of how little is needed to be lethal. You really don't want to be spewing it over the countryside in a flaming ball.)