1. Why is it that no matter what colour bubble bath you use the bubbles are always white?
This always bugged me too, until I started dumping a gallon of food coloring in with every bath I took. It's alot more fun now. Sure you might come out bright purple too, but its worth it.
2. If nobody buys a ticket to a movie do they still show it?
I always wondered this too. If someone knows for sure which it is, I would be
very excited to know.
3. Why do people constantly return to the fridge with hopes that something new to eat will have materialised?
Maybe they're just really bored? I used to do this I guess, but I've evolved to the point where I actually think ahead now. I only get up if I know what I want, and I know it's actually there.
4. If prunes are dehydrated plums, where does prune juice come from?
YEAH WTF?! 
5. If there's a speed of sound and a speed of light is there a speed of smell?
Nonsubmissivewife's answer to this is perfect.
6. Do prison buses have emergency exits?
Yeah, but they're probably padlocked.