Well on Hugg I found this linkhttp://blogger.xs4all.nl/marcg/archive/2007/01/09/171574.aspx  A quite annoying tactic for sure.  I would not like someone putting anything on my car.  The ironic thing is that they are protesting a petroleum product, gas.  Yet they are making pollution buy the exploding balloons.  Originally I thought the balloons were made from petroleum also, but I guess they are latex or rubber.  Either way it is ironic that it is OK to pollute if you are protesting pollution.