1. be multiple developers on the same project.
2. for each developer, use your own tools and techniques, insist on only handling those parts of the site that you did with your tools, and insist on never fully understanding those remaining parts of the site the other devs did.
This will allow for all sorts of fun, including:
- A multiple inconsistent implementations of the same thing
- B even better, those multiple inconsistent implementations affecting and breaking each other!
One you have this going, there are some easy bonus pickings: Whenever B happens, "fix" it with weird extra incancations inside your own toolset, cleverly avoiding any attempt at (2) above.
If you succeed at this, several developers can, combining these techniques to sabotage and trigger a veritable pinball game of strange breaking effects.
Note: CSS is a great place to start this game!