In software development, and I imagine in many other fields, we often make up temporary nicknames for new projects or features. These are not meant to be the real names for the end product and are often funny, playful, or sarcastic in nature. These are also not intended to be "codenames" that hide the nature of the project or feature. Is there a word for such nicknames?
Working title or Production title
According to Wikipedia:
A working title, sometimes called a production title, is the temporary title of a product or project used during its development, usually used in filmmaking, television production, novel, video game development, or music album.
Working titles are used primarily for two reasons — the first being that an official title has not yet been decided upon, with the working title being used purely for the identification purposes, and the second being a ruse to intentionally disguise the real nature of a project.