I've seen one before where they slammed the bottle right after they put all the mentos in there and it rocketed upward. That's a pretty cool picture though.
yeah, I had to try that too eventually.. I kept hearing about how it would explode but wouldn't believe it, so I tried, and that happened.
Me and my friends did it once, and the bottle jumped up and hit this sleeping bum in the head. I felt kind of bad, but I must admit that we didn't see the bum... he was in the shadows.