To make it more handy, if its just documents, store them in a flash drive..or as already said, set a password. Or if you cannot avoid having your friends tinker on your laptop, create/add a guess user for your friends and separate yours as an administrative user..this way they wont be able to access your personal files...in addition, change the properties of your documents to hidden to make them invisible for the moment so if you happened to forgot logging-off and left your laptop logged-on for friends while taking a pee..:)