ענק - דרך יצירתית למנוע משכנים לגנוב לך אינטרנט אל-חוטי

Sure you could just password protect your wifi, but where would be the fun in that? This guy shows how you can make changes to your router configuration (I guess you need a linux router to do this) so that anybody who steals your wifi will see all images on websites upside down and other fun tricks.

http://www.ex-parrot.com/~pete/upside-down-ternet.html