How to Black Text on 4Chan
When discussing films, video games and books on the Internet, it is considered polite to avoid giving away key plot points. These key plot points are called spoilers--so named because they spoil the surprise for users who have not yet experienced the film, game or book. To keep plot points hidden on 4Chan message boards, you can use "spoiler" tags, which create a black background behind words and phrases. The effect of the black background combined with black text renders the "spoilers" unreadable unless you place your cursor over the text or highlight it.
Launch your Web browser, and navigate to the 4Chan website.
Click to select a board from the "Boards" listing area.
Click the "Reply" link next to the first comment or image that appears in any post.
Type your name in the "Name," "E-mail," and "Subject" information in the displayed text fields.
Type "[spoiler]" in the comments section to open the spoiler tag.
Type the words that you want to have appear as black text on a black background.
Type "[/spoiler]" to close the spoiler tag.
Click "Submit" to submit the post.