In the brotherhood of gossip columnists, there is or at least used to be an unwritten rule: don't go after the personal lives of rivals, because they can always retaliate. So why would the New York Post's Page Six publish sex chats between corpulent blogger Perez Hilton and one of his online admirers? (Yes, he has them, amazingly.)

Here are some theories.

1. Page Six still bears a grudge; before there was perezhilton.com, the celebrity gossip maven published as pagesixsixsix.com. The Post had to threaten a lawsuit to stop Perez's joke on their name. The Post's own website, which launched late last year, is still lagging by comparison with the blog upstart; maybe the gentlemen's rule that protects print competitors doesn't apply in the brutally competitive world of web gossip.

2. When the Post's Paula Froelich is off duty, as she is this week, head honcho Richard Johnson tends to revert to old-fashioned baiting of women and gays. He's the one, after all, that made cheap digs at Vanessa Grigoriadis' supposed moustache when the New York writer dared describe Page Six as "emasculated".

3. The Post is merely pushing its own story forward. Last month, the Post's psychic predicted this turn of events for Perez: "His love life continues to suffer (no soulmate yet) but he will be in a love triangle - i.e. an affair with a very famous celebrity, making scandalous news himself."

But the most likely and least interesting theory? A crank sent in lurid chat transcript in which the world's most successful gossip blogger suffered the kind of embarrassment he's inflicted on celebrities. And that was, rule or no rule, irresistible.