nippy
Explanation
The Joke
The comic shows a man looking down at his chest in horror, exclaiming "What the?! Okay, who programmed my nipples to be unicorn horns?!" His nipples have been replaced with small pink unicorn horns poking through his shirt. The caption below reads: "Should never have released the API for my body."
The joke imagines a future where the human body has a programmable interface (an API, or Application Programming Interface), and this person made the mistake of making it publicly accessible. Just as open software APIs allow third-party developers to build on and modify a platform -- sometimes in unwanted or absurd ways -- opening up a body API has allowed some unknown prankster to make ridiculous modifications to his anatomy.
The Humor
The humor comes from mapping a very familiar frustration in the tech world (the chaos that ensues when you release an open API and random people start doing unexpected things with it) onto the human body. Anyone who has worked with public APIs knows the experience of users doing bizarre, unintended things with your system. The specific modification -- unicorn-horn nipples -- is deliberately silly and juvenile, which contrasts with the dry, technical framing of the complaint. It is the kind of body modification that is clearly a prank, underscoring how open platforms inevitably attract trolls.
References
An API (Application Programming Interface) is a set of protocols that allows different software systems to communicate. Major tech platforms like Twitter, Google Maps, and Facebook have public APIs that allow third-party developers to build applications using their data and services. The joke plays on the well-known risks of making APIs too open or permissive.