To submit a page that links to some content of interest—rather than a link to the content itself—to an aggregator (reddit, digg, etc.), presumably to drive traffic to the intermediate site.
He submitted a direct link to the video under the title “Video of dog farting (non-linkjacked version)”
by f schmiddy March 30, 2006
To post something on reddit that was previously posted to Digg.
Did you see that story on reddit? Yes, it's a linkjack from Digg.
by noynoy-a September 16, 2010