What will 3 hours give you that 30 minutes won't

I recently passed a phone interview to be advanced to the next round - the in person interview. I was asked when I would be available for the three hour interview.

Three hours?!!!

What can I possibly tell them in three hours that I cant tell them in 30 minutes? How could I even possibly fill a three hour interview when I only have enough technical knowledge to talk about computers for about 45 minutes?! I've given this a lot of thought and come to the following game plan:
1. I'll start with the 45 minute of tech talk where I will name every namespace and t-sql command I know.
2. I will then spend about 10 minutes discussing my hobbies.
3. I could then ask for water killing 2 minutes.
4. Next I could probably stretch a detailed account of my childhood into about a 20 minute discussion.
5. I could then ask to use the restroom and kill 4 minutes.
6. Then ask for more water killing another 2 minutes.
7. At this point I can burst into a passionate discussion of coffee for about 5 minutes.
8. The coffee talk will be a natural segway into 10 minutes of me rocking back and forth and practicing making random sounds like I did when I was a baby.
9. Completely drained of ideas, I will take a nap until the three hours are up.