Yawning is contagious

Now i know why i will fall asleep after my classmate yawn and then sleep in LAN class and thinking skill class (sometime chemistry class)

From
http://www.livescience.com/bestimg/index.php?url=myths_yawning_03.jpg&cat=myths

Empirically, this is tough to deny; perhaps you'll yawn while reading this. The real question is whether there's actually something physiological at work here, and the answer is likely yes: even chimpanzees mimic each other's yawns.