Codecademy's Joke

In an introduction to an objects course the team of Codecademy placed a javascript joke. I am not a member of the team of Codecademy but found it pretty funny. Here is their joke:

"We at Codecademy love to joke around. Obviously different things make different people laugh. This first 'joke' is super geeky because it involves coding! And it'll only be funny if you knew the TV show 'Batman'. But we loved it and hope you do too! Copy this code into the scratch pad and run the code!

Array(16).join( 'hero'-1) + "Batman";