As a hip-hop writer you want to engage your audience and make them active listeners. You want them to say "what the fuck was that, that sounded dope" and rewind.
There are many ways to achieve this.
1. Say something off the wall and surprising. This will depend on your style and your reputation with the listener.
Ex: "Rhymes is made of garlic" - Ghostface
2. Say something that provokes thought.
3. Use a complex rhyme scheme.
4. Use inventive wordplay.