First, there was Second Life. I've signed up, but I have enough self-awareness by this age to recognize what a thief of time this could be for me.
Second, there was First Life, or more accurately Get A First Life. This competent parody site had a link that invited cease-and-desist letters to be posted on the author's blog.
Third--oh, well-played indeed--Linden Labs's lawyer responded with a parody of a cease-and-desist letter. Memorably, Ginsu Yoon replied in pertinent part:
Linden Lab objects to any implication that it would employ lawyers incapable of distinguishing such obvious parody. Indeed, any competent attorney is well aware that the outcome of sending a cease-and-desist letter regarding a parody is only to draw more attention to such parody, and to invite public scorn and ridicule of the humor-impaired legal counsel. Linden Lab is well-known for having strict hiring standards, including a requirement for having a sense of humor, from which our lawyers receive no exception.