The __DATA__ segment at the end of the file stores data in what Perl interpretes as some sort of pseudo-file. To read that out, you can use the filehandle DATA.

What TJPride does here is reading out all the lines as array and joining them into a single string. (Reading from < DATA > in array context since it is the array argument to join).

BREW /very/strong/coffee HTTP/1.1
Host: goodmorning.example.com

418 I'm a teapot