Ok, I'm intrigued. And a bit confused.
Why is it called a 'slug'?
For those of you that don't know what I'm talking about, or are wondering why I'm asking about living boogers on a technical coding site, a slug is essentially a human-readable version of a primary key.
In blogging and other CMS, the slug usually makes up the 'permalink' for the document. For an example, see this document.