stolen from pombagira who pulled it from someone else who pulled it from yet another person :) Yes, this is signal boosting.

Passing this along from my flist.

Thanks to midniterose, here is how to stop the crossposting of comments/entries from LJ to sites like Facebook:

There is a way to disable everything. Here is what you have to do:

1. Go to your "Journal" menu, and select "Journal Style"
2. To the right, you'll see what theme you're using, with a link stating "Customize Your Theme". Click that link.
3. Scroll down a little ways, and you'll see that on the left side of your screen, you have multiple options to modify your theme. Click on the "Custom CSS" link, and it should load the options for doing Custom CSS.
4. From here, all you have to do is go to the "Custom Stylesheet", and put in that line.

.b-repost-item {display:none}

once you have it pasted in there, save changes.

Feel free to PASS THIS ON!!

ETA: This prevents the "repost to FB/Twitter" ticky boxes from being displayed when someone comments on one of your posts. It seems to work, UNLESS the person is viewing your page in their own journal style, in which case it might not work.

ETA2: Inserting the code below in your custom CSS box reportedly works for more kinds of journal styles, including custom ones (this courtesy of xnguard):

.b-repost-item, FORM#qrform > TABLE[style="border: 1px solid black;"]:last-child TD[style="vertical-align: top; text-align: right;"]:first-child { display: none !important; }