As long as there has been a Joker - and we're going on 80 years with this guy - there has been, as well, a Joker venom. It debuted alongside him, in 1940s Batman #1, and has been a part of his arsenal ever since.
Gif: Batman, Gizmodo
Though its side effects have varied over the years, it has remained in each iteration a gruesomely unpleasant murder tool (or non-fatal face-mangling tool, as the case may be). The uncontrollable laughter isn't so bad, but the rapid shutdown of all heart and brain function is, I'd argue, extremely bad. Worst of all, though, is going to the grave with that iconically hideous grin.
But could such a toxin actually exist? No single one of its effects would seem impossible to reproduce in isolation, but a venom with all or most of them is a different question - one which forms the basis of this week's Giz Asks, for which we reached out to a number of experts on the subject of venom.
I think the answer is, "it depends."
It's theoretically possible to induce random laughing fits, because that's one of the symptoms of a disease called Kuru (kind of like Mad Cow). The disease is caused by a misfolded protein (a prion) that people can get into their bodies when they consume tissues laden with it... which, in the case of Kuru, was discovered because of cannibalistic traditions. The prion induces properly-folded versions of itself to misfold, and the accumulation of these "bad" proteins leads to brain lesions that can cause neurological symptoms like laughing fits.
So you could, theoretically, create a drinkable liquid or an injectable with such toxins that would induce laughing fits by causing brain damage. That brain damage is irreversible, so it is eventually lethal, too. Of course, the creation of these lesions takes time - years, even decades, in cases of Kuru - so it wouldn't be the instantaneous onset of laughing fits. You might be able to engineer a prion or something else that works faster, though. Maybe. I don't think anyone has tried, of course.
There are also illicit drugs which induce euphoria, which could potentially make someone laugh. Though it wouldn't be forced, uncontrolled laughter like with brain damage so much as extreme joy and happiness, which might sometimes or frequently present as laughing fits. It would likely be difficult to create a drug that was targeted enough to cause such euphoria almost instantly without throwing off the rest of the body and brain (thereby killing the victim before they get to the happy, giggly place). So I'd say it's possible, but probably really unlikely, that a "laughing drug" which reliably induced laughing followed by paralysis could be developed.
So, in short: It might be possible to create a chemical cocktail that makes people laugh uncontrollably and die, or one that makes them really happy and giggly and then die, or simply die really quickly from rigid paralysis. But the characteristic joker face in death is unlikely.
Oh, and none of this could be done in a closet by mixing cleaning chemicals. This would be serious designer lab stuff, probably cost a fortune to make, and likely require special storage and handling.
Assoc. Professor, Australian Institute for Tropical Health and Medicine
There is no venomous animal on the planet that could do [everything the Joker Venom does]. Having said that, there are components of different animal venoms in the animal kingdom that could, in combination. My understanding of the Joker is that he's quite a smart chemist, so it would be possible to extract the components from those venoms and put them all together.
If you were looking for a component of a venom that caused cardiac standstill very quickly, you could get that from boxed jellyfish venom. A large quantity of of boxed jellyfish venom, in a human, would cause cardiac standstill within seconds. And if you diluted it, it could take minutes, depending on what you wanted to do with it.
If you were looking for a contraction of facial muscles, the Cone snail's venom does exactly that.
Shutting the brain down is a little bit more difficult, because of the blood-brain barrier. To make that happen, you'd have to inject the venom directly into the central nervous system. But there is a wasp that does that. Basically, it injects the venom into the central nervous system, and it goes straight to the brain. So it has to go in through the spinal column, or the brain itself.
But, if you wanted to cause paralysis of the nervous system, that's quite simple. There are a variety of animals that do that. One of those is the Blue-ringed octopus, whose entire venom is aimed at causing nervous pulse cessation. Someone that's stung by one of those animals is completely alive, but they can't move any of their voluntary muscles.
So: If you were to mix the toxin from a boxed jellyfish, the toxin from a Cone snail, and the toxin from a Blue-ringed octopus, then you would cause cardiac standstill almost instantaneously, you would cause all the muscles in the face and body to contract, and you would cause all neural cessation to stop throughout the body. Eminently doable!
Would this venom need to be directly injected, or could it be transmitted through the air?
If a toxin is injected - if you're bitten, or stung - it's a venom. If the toxin is ingested or inhaled, it's a poison. Botulinum, which is a poison, causes contraction of muscles, and that could be [made into] a gas - but it wouldn't cause cardiac standstill. I don't know of any ingested poison or ingested toxin that would cause cardiac standstill in a short period of time. They just don't work that way.
PhD Student in Biological Physics, Structure and Design at the University of Washington
Unfortunately, people have already concocted compounds at least as horrible as the Joker's venom. And yes, the Nazis are involved.
In the 1930s, a German chemist named Gerhard Schrader was trying to invent a new kind of pesticide. He claims he wanted to end world hunger. In the process, he stumbled on a class of phosphorous-containing compounds so nightmarishly lethal that the Nazis - who he worked for - refused to deploy it. Schrader is now known as the "father of nerve agents," having boosted the toxicity and deliverability of his compounds.
He wasn't the only one. Scientists in the UK and Russia eventually tried their hands at these dark arts, producing some of the most toxic chemicals the world has ever seen. Even brief exposure to strong nerve agents, by air or by skin, can lead to excruciating whole-body muscle contractions and death by asphyxiation within minutes. And despite being banned everywhere on Earth, we've seen the Syrian and North Korea governments use nerve agents during the Obama years.