1: Danbooru was a popular board for cartoon porn. When the owner largely closed it to non-members, simultaneously disabled signups, and announced that he would crack down on certain types of pictures. For example, furry pictures were forbidden, whereas bestiality was perfectly acceptable. Breaking these rules would result in banning.
Some people were less than pleased, and the resulting shitfest made the owner close the site within two weeks.
2: Anything deader than dead.
3: The act of taking your toys and going home when things aren't going your way. Also: Individuals reacting in such a manner.
4: Giving up.
5: Someone that doesn't like having fun.
1: "Danbooru, much like disco, is so very, very dead."
2: "Christ, look at that Danbooru roadkill."
3: "Fuck you guys! I'm out of here!" "Yeah, fuck off, Danbooru-boy!"
4: "Guys, I can't do this. It's too hard." "Come on, don't pull a Danbooru on us now!"
5: "Hey Moe, want to hit the bars with us?" "No, I'm staying in tonight." "Come on, don't be so Danbooru."