Trump’s BS.

The GOP

Highly concentrated dihydrogen monoxide.

But for real though, I have no idea.

So far haven’t found any that have SA on the bottom, but here’s a list of fucked up shit that might be in the shipping vehicle next to you:

https://chemistry.stackexchange.com/questions/4135/is-there-any-substance-thats-a-4-4-4-on-the-nfpa-diamond

https://en.wikipedia.org/wiki/Tert-Butyl_hydroperoxide

https://en.wikipedia.org/wiki/Tert-Butyllithium

https://en.wikipedia.org/wiki/Pentaborane(9)

https://en.wikipedia.org/wiki/Diborane

https://en.wikipedia.org/wiki/Monomethylhydrazine

Also, from stack user Matt_Black

I think chlorine trifluoride deserves a mention

One of the issues with relying on published NPFA triangles to judge the answer to this question is that some of them don’t seem to be very reliable given the known properties of compounds.

According to one of its suppliers ClF3 has a rating of 4-0-3. So it would not count very highly here. This seems about as inaccurate as describing dimethylmercury as only mildly toxic. I mean how in hell can it have a zero on the fire score and only a 3 on the toxicity score?

Here is how John D Clarke describes it in Ignition (his history of rocket fuels):

It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water—with which it reacts explosively. It can be kept in some of the ordinary structural metals—steel, copper, aluminum, etc.—because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal–fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.

So for example, while the compound itself is arguably not flammable, absolutely everything else is flammable in its presence. And given that those reactions tend to produce far more benign compounds like HF gas, it can hardly be considered as only a 3 on the toxicity scale either (though, perhaps, if you are dead already from the corrosive or explosive effects of its reactions, the toxicity is not a major concern).

To put it mildly, ClF3 is one of the most dangerous compounds that is commercially available on any reasonable metrics and damn those published NPFA triangles.

There’s a rocket fuel that fit’s that description, forget it’s name though.

A web search found a few substances that are close, but none that match exactly:

• diborane is 4 4 3 W
• tert-butyl-hydroperoxide is 4 4 4 OX
• tert-Butyllithium is 4 4 4 W