To initiate someone into the Tubgirl club, by sending them to said website.

This is usually accomplished through subterfuge, by setting the website to launch on boot, by resetting a desktop shortcuts properties remotely, or utilizing www.tinyurl.com to mask the "payload" address.

Sending someone a disguised link either over IM or in an e-mail that links to the famous tubgirl photo. Can also be done by printing out the photo and then stashing it where an unsuspecting victim will find it.