This is a list of spam floods on /b/ that I came across in the /b/ archive.
HAVE U EVER SEEN A SQUIRREL TAKE A CRAP? - April 9 2006. Earliest flood available in the archive. Consisted of the words "HAVE U EVER SEEN A SQUIRREL TAKE A CRAP?" repeated a few dozen times (it varied, sometimes having 18 repeats where others had 39). It almost always came with an image, although it is currently unknown what it was. No reference of it found anywhere, which is suprising considering it was fairly common. Very minor, although it brings up an important zoological mystery. It can be viewed in its full text here.
Xena fanfiction - April 9 2006. Sometimes in the middle of random threads someone will just begin posting excerpts of a heavily misspelled Xena: Warrior Princess fanfiction that can found here. It was also posted with a currently unknown image. In this thread here it happened about 10 times. There were several threads that was just several copy and pastes of the fanfic, such as this one. This essentially certified the flood.
Furcism is as bad as Racism - April 9 2006. A copypasta of a furry who claims Furcism is as bad as Racism. The text of the pasta is available here (at the top), and was known to be posted with a picture of Ghandi. Occured not long after the Xena flood. Dozens threads were made with just that copypasta, much larger than the other floods of the time, and Anti-Furry copypasta also began being flooded on a lesser scale (at the later points of the flood someone started flooding the flood threads with literal gibberish by slamming their keyboard). It was referenced in another thread here with the text "Too bad the thread was aimed at ALL furries, not just the guy who's spam-flooding /b/ with that fucking picture." Later in the day, an emergency Caturday thread was called in order to counter the furry spammers, available here.
No, I am Fred Gallagher - April 9 2006. As copied from the memes page: Completely meaningless. Refers to the artist behind Megatokyo Fred Gallagher, but is posted completely randomly, mostly in response to the OP (regardless of whether the OP post was in the form of a question or not), although in one thread it was spammed in response to random people posting four times. Usually posted only once per thread but occured over several hours.