what is the meaning of head fake

Question

Answer

I read Randy Pausch's last lecture in which he talks about fulfilling childhood dreams and goals. 
Randy Pausch was an American professor of computer science and human-computer interaction and design at Carnegie Mellon University (CMU) in Pittsburgh, Pennsylvania. He wrote the speech before his death from pancreatic cancer (2008). 
Personally, I find the speech wonderful and inspiring. He said that the lecture was for his kids, but I believe it's a valuable life lesson. 

At the end of the speech, he asked the audience whether they figured out the head-fake or not'. He explained that 'a head-fake occurs when someone is taught a deeper lesson under the pretense of learning something simple — when a high school football player learns determination, teamwork, and perseverance while seeming to learn a proper three-point stance, for instance.' And he added 'It’s not about how to achieve your dreams, it’s about how to lead your life.' 

The 'head-fake' occurs when a footaball player carrying the football moves his head quickly to one direction as a way to trick the other player and make him think that he's going to run in that direction. 
Randy Pausch uses the expression at the end of the lecture to tell the audience that the aim of the lecture is not to teach you how to achieve your dreams but how to lead your life. 
This is the 'head-fake' of the lecture. The audience learnt a deep lesson from the lecture in which Randy pretends to talk about a simple thing 'How to achieve your childhood dreams'. :)