The Moebius Strip is one of the most famous shapes in mathematics, but also famous in real life. Its extraordinary "one-sided" shape stands for "infinity", "everlasting friendship", etc. The Moebius Strip may be realized by taking a long rectangular strip of paper, turn one of the two shorter edges by 180 degrees, and then glue the two shorter edges. In this way, when starting to "walk" at the glueing position on one side of the object, and continuing to walk on that side, one eventually ends up at the same point of the Moebius strip, but on the other side! Without having crossed the boundary of the shape... Thus, the Moebius strip actually only has a single side!!!