The defacto compression algorithm for the Macintosh (or a request of a person you don't like). Put out by Aladdin Systems, this age-old program handles all of one's Mac compression and decompression needs. It also handles the resource fork that is unique to the Macintosh file system.
It's one of the Macintosh's killer apps, and it's free to download the expander. It's a necessary utility for any macintosh these days. It is comparable to the zip format on the PC, and all of one's Internet downloads are in this fashion.
I still think it is also a compressed version of a request, of the form: "Just take that file and go... "