Don't do it. It's annoying. I go to the front page to know who's online and who isn't, so I can know when to expect the next post to come up. If you're appearing offline, I don't get that accurate representation, and I remind myself next time that if I'm waiting for a post from someone who appears offline, I waste my time going through the old rp's to find a post by that person to see if they are actually online or not. Lying about your online status is lying.
And lies make baby Jesus cry.