Technical debt in your file headers
Here's a little article about the "file header tax", lines of boilerplate at the top of files that serve no purpose. Copyright notices, disclaimers, maybe even some revision history, it's all just clutter, and clutter is technical debt.
Take a look at the next file you edit. Is there anything at the top of it that is not functional code? Ask yourself if it really needs to be there. If in doubt, throw it out.