There's no real-world equivalent of "ACME weapons" in the sense of a brand that makes absurd, cartoonish weaponry.
However, the term is often used in a humorous way to refer to:
* Unconventional or improbable weapons: Like the Acme Rocket-Powered Roller Skates or the Acme TNT, the term can be used to describe any weapon that seems ridiculously unrealistic or impractical.
* Products that backfire spectacularly: ACME products are infamous for their tendency to malfunction, causing chaos and mayhem. This can be used to describe any device that unexpectedly goes wrong, especially if it results in humorous or exaggerated consequences.
So, while "ACME weapons" don't exist in the real world, the term has become a playful way to describe anything that fits the cartoonish and unpredictable nature of the brand.