Shoulder pads

On Friday evening we watched a family movie about an ordinary kid determined to play with Notre Dame football team.  William loved the football playing scenes and he imitated them all during the movie.  

At some point he changed into his football jersey, and after the movie was finished, I noticed that his shoulders had pads of some sort.  I said, "William, what are those pads on your shoulders?"  

"Socks," he said.