Adds Ruby code to a PNG file. This allows foxes to run a PNG file as Ruby code, while keeping the PNG file intact and viewable. It basically just adds the "ruby" ancillary FourCC to the PNG spec and throws the code in.
If you read the PNG spec, you'll notice PNG is just like bacon.
The foxes are licensed by why the lucky stiff under the CC BY-SA 2.0 license, and are part of why's (poignant) guide to Ruby.
$ ./foxify foxes.png bacon.rb output.png
$ ./foxes output.png
Chunky bacon!!
Chunky bacon!!