Diet Coke & Mentos evangelism

So on my trip recently to Indy the people i was travelling with were apparently obsessed with the trick where you put mentos in a 2-liter of diet coke and it fizzes out so fast that it shoots up like a fountain. We did it in the parking lots of several gas stations and our hotel. The funny thing i noticed is that a lot of times a few people will stand by to watch you do it. We never actually got to "witness" to anybody, but we were driving a church van and sometimes it would come out that we were youth pastors. It just seemed cool because usually you don't really interact with the people you run into at a convenience store - and just by shooting off a "diet coke bomb" we were able to at least talk to people a little bit.
P.S. nobody seemed to mind that we were doing it as long as we didn't get coke on anything and we picked up our trash afterward. Even the police at one place thought it was cool :)