When you can think of only one brilliantly witty, unique and (of course) effortless line to post on a social networking site eg. on Twitter, as your status on Myspace or Facebook, you just 'double up' and use it for more than one of the sites. Therefore you will seem brilliant, as long as none of your friends are on both/all the sites you use the line on.
Girl 1: I saw your brilliant 'nail polish dries slow on nails, but quick on carpet' line on Twitter.
Girl 2: Oh, thanks.
Girl 1: Yeah. Then I saw it on Facebook.
Girl 1: Oh, shit.
Girl 2: That's right! You got busted update doubling!