An internet term that is short for "in before" used when someone replies to something before something that they anticipate to happen eventually happens.
Generally used on internet forums, inb4 refers to a user posting a reply to a message/topic "before" another user posts an obvious response. When used appropriately, inb4 is followed by a word or short phrase that the user knows will eventually appear in the topic conversation.
Jonny113: Jiraiya would beat the crap out of Itachi.
Steven387: inb4MS
Mike128: You know Itachi has MS, so Jiraiya doesn't stand a chance.
Stands for "in before". You or whoever is saying it is "in" before something happens. For example, if your on a message board, you are "in" it so when you say inb4 you mean to say, "I'm in before... such and such happens!". Usually used to predict an unfortunate event similar to the PepeLaugh emote.
Started on MLPForums, this refers to posting in a topic before ghostfacekiller39 that speaks badly of the character Rarity from My Little Pony: Friendship is Magic. ghostfacekiller39 is perhaps the most dedicated Rarity fan on the forums, and he's always quick to defend her when the need arises.
RarityHater69: "Rarity is the worst pony ever, she's such a bitch I hate her!"
GenericName123: "inb4 ghostie"
ghostfacekiller39: "(Long profound rant about why OP is wrong, with lots of Rarity smiley faces mixed in)"
An abbreviation used on messageboards like /b/ in anticipation of a certain image, event, or meme occuring.
"In b4 Togepi" = I am sure that any second now, a picture of Togepi will be posted to this thread.
"In b4 b&" = There is no doubt that someone is about to get the banhammer because of their churlish behavior.
"In b4 v&" = I am quite certain that the FBI will soon be showing up to take us all for a ride in the party van, and if such a thing happens, you can't say I didn't see it coming.
Sister: This meeting was to discuss the rough draft of my essay, where we discussed the subsidiary questions I added in my rough draft. We also discussed the relationship between my main title and the real-life situations I chose to use in my essay. We discussed the structure of my essay as well, specifically the Math AOK section and how it relates to the contradiction of the title. This second meeting was particularly helpful in discussing the implications of my essay claims and how to apply the title across various areas of knowledge. There were many sections of the essay that could have been cut down in wordiness and the ways of knowing required further and more in-depth analysis.