Borrowed from Reddit and Twitter:
Everybody has a testing environment. Some people are lucky enough enough to have a totally separate environment to run production in.

I don't always test my code...

Get Vagrant and set it up the same as prod, it’s 2018 people come on xD

TechSupport: "yo dev1 somebody just called this program keeps crashing on him! Come take a look pls"
Dev1: "wtf is this! Jonii come look! You've worked on this the most."
Me: "wtf. Oh. Ehm. How can I look up where I compiled my code to?"

Turns out I compiled code I'm still working on in production and the existing program obviously couldn't handle my spaghetti.