A post from the top submissions gets featured on the official Boldomatic stream via a repost.
A jury will decide on the winning post based on popularity, quality of the post, and how well the content matches the contest. The more clever, sneaky or smart the post, the better it has a chance to win.
You are free to submit posts in any language, however winning posts are almost always English so that most users can understand them. You can win a contest more than once, but the jury tries to give everyone a chance as much as possible.