To put stank on the source code is to modify any electronic or mechanical object so that it alters the items original function.
Person 1: dude, are you watching gay porn on the head unit in your car?
Person 2: yeah man, I dropped some stank on the source code, and now my car dashboard streams porn 24/7
To put stank on the source code is to use mystical and ancient knowledge of IT to fix or improve the function of electronics.
If you've ever had a problem with your computer, and your geeky friend fixed it seemingly by magic, that's when you know that they dropped some stank on the source code.
Person 1: Woah man, are you watching porn in 8k?
Person 2: Yeah dude, I dropped some pretty serious stank on the source code, and now I can stream anal porn in ultra high quality
Person 1: My phone is so slow. I think I need to update my software
Person 2: Fuck that brah, just put some stank on the source code!