TL;DR No one else can read the program I wrote so I no longer have to worry about being fired.
I was assigned a huge that was supposed to take 6 months to code, and casually asked if it mattered what language it was in. I was told it didn't matter, and I wrote it all in Python. No one else at the office knows how to use python. My boss (bit of an ass) kept asking for new features without warning, so it took a little under 18 months to finish.
I also added some features that help me automate menial tasks, and long story short, this program now does 1) what it was required to do, and 2) most of what I'm supposed to do now. I think my boss has caught on to the fact that I am taking A LOT of breaks but still completing about 1.5x the work I'm assigned. The thing is, he cannot get rid of me, because I am the only one who knows how to use the program. No one else knows Python, and on top of that, almost all the code is uncommented because I was told that I would be the only one working on the project, so even if they knew Python, they would have to spend at least a few months learning how to use it.
The cost of rehiring and training someone to use the program seems to be more than my boss is willing to pay, and firing me would bring my branch to a halt for a long time. So basically I don't have to worry about being fired anymore, which is a HUGE relief.
I don't want to sound malicious. I wasn't actively avoiding others being able to read my code, it just happened to work out and I am very grateful to be in this unlikely position.