What's the easiest and fastest way to open one of those hardpack vacum plastic packaging thingies?

Just bought a new memory card for my phone and it comes in one of those hard plastic packings that basically are impossible to open without having a chainsaw, the FBI and the CIA, a tank and 245 marines to help you.
Example: http://www.techpowerup.com/reviews/AData/16GB_Turbo_Compact_Flash/images/packrear.jpg