It works on my machine" and other lies we tell our DevOps team

There is no sentence in the tech industry that triggers a DevOps engineer faster than: "Well, it works fine on my local machine."
We have all done it. The build fails in production, the pipeline is screaming in bright red, the client is panicking, and the developer is sitting there calmly spinning containers locally without a single error.
The gap between a local environment and staging is where engineering sanity goes to die. It’s usually a hidden environment variable, a slight version mismatch in a package, or pure dark magic.
As we head into the weekend, what is the most ridiculous "local machine" bug that completely broke your production environment this week? Let's share some deployment trauma in the comments.
P.S. If your code only works locally, check out my profile bio for the official badge of honor.