Many gestures, such as how you say “yes” or “no” are country-specific, but others are universal. For example, all people wrinkle their noses and raise their top lip to show they find something horrible, even though the things which actually disgust us are often very different. Everyone knows what a smile is, too, and when you are only pretending to smile. This is because muscles around the eyes are linked to the emotional part of your brain, which are very hard to control, and they only work when you really mean it. Also, a real smile will fade after a few seconds, whereas fake smiles will last much longer.