Surprise boxes are funny memes implemented by the mods that are used to conceal text and images. Le mystery surprise boxes were added on December 13, 2014 and were upgraded to contain custom made surprises on December 15.
But wait! How do I use surprise boxes? :0Edit
dont rush me bitch
To surprise-ify text, add [spoiler]you're comment goes here[/spoiler] around the text you want to be surpriseded. To spoiler images, check the [Spoiler?] box next to the "Post" button.