I ran a search on google for the "set ~ operator" (because i was just randomly searching for information on set operators because i studied them last semester and wanted to find a tidbit of info).
Interestingly enough, it brings up nothing about the ~ operator, or any set operators at all, but instead brings up the following site:
http://members.iinet.net.au/~bofh/index.html
Not having a clue what it is, I click on the first link:
http://members.iinet.net.au/~bofh/bofh/genesis1.html
it's hilarious