The code has long been lost to the great pastebin in the sky, but my first serious PHP project was an absolute nightmare. I built a disbursement tracking system for a local food bank/church while I was in high-school (~6 years ago).
The system was your basic CRUD application that tracked who the food bank gave money/stamps/assistance too. It also allowed them to generate some fancy reporting.
The code was so. damn. bad. This was before I even knew what an MVC framework was. The "main" control panel page was a single, enormous PHP script that was switch-cased. There was zero data validation, zero security, zero maintainability. It was a nightmare in retrospect.
To be fair, I did it for free and the church loved it, so oh well :)