There is a new survival TV series out called naked and afraid. The gist of the show is that they take two people (a man and woman) and put them into a survival situation with nothing except for one personal item each in a cloth bag. No clothes, no shoes, nothing but that one item. The challenge lasts 21 days. Now personally I would never bet my survival on one item but it is kind of fun to consider the possibilities. To avoid the obvious KNIFE answers lets say you know for sure that your partners item is a knife. What would your one item be? Additionally, if you feel like mentioning a specific knife feel free to do so. I'm thinking a large clear heavy duty plastic sheet. You could use it to make a solar still, to catch rainwater and for waterproofing a shelter.