Ah 4chan..

1

Voted Kim Jong Un the Times Magazine's Person of the year for 2012.

Of course, the Times knew it was pranked and subsequently elected Barack Obama as the Person of the Year for 2012.

2

They sent Pitbull to perform at a Walmart in Alaska, Kodiak - the most remote Walmart in the world.
And he actually went.

3

They tried to send Justin Bieber to North Korea.

4

They hijacked The Times's 2009 Most Influential Person in the World poll.

5

They rampaged Wired's Sexy Geeks 2009 Contest with moot (Christopher Poole).

6

They annexed a poll which would see Taylor Swift perform at a school with the most votes.
No, she didn't perform there but did donate 50,000$ to the school.

7

They took over a Mountain Dew poll for a new bottle with "Hitler did nothing wrong".
There was also Gushing Granny, Fapple, Diabeetus, Fapulous Apple and a half a dozen other Grannies among them.

8

Helped name a whale near Hawai Mr Splashy Pants with Reddit and Boing Boing.
The whale was actually later named Mr Splashy Pants (https://en.wikipedia.org/wiki/Mister_Splashy_Pants).

9

They petitioned the US government to label BLM as a terrorist cell.

10

They blitzed another Taylor Swift poll when one of their fellows friend (39 yrs old) wanted to meet Taylor Swift to crush little girls dreams and to sniff her hair.

11

Started with a twitter hashtag #Cureformiley which led many fans to believe that she had contracted HIV/Aids. 4Channers even made a fake facebook account, a fake Liam Hemsworth twitter account (due to their recent breakup at the time), a fake CNN article, a fake screenshot of a TMZ video with most fans believing the prank and subsequently made fan art and a few donations.

A few updates on Facebook I found.

12

They chose the picture for a Norwegian company's soap.

13

They managed to put a rageface on Prill's dishwashing liquid in Germany.

14

Were close to choosing Kinder's chocolate new face in Kazakhstan.

15

Brainwashed Microsoft's IA bot Tay - whom became a Nazi. Just over 24 hours from loving humans the bot took a dark change due to 4chan and 8chan's conversations with Tay. Tay was then quickly shut down and her tweets deleted.

More of Tay. Also a few tweets here: http://twitter.com/geraldmellor/status/712880710328139776/photo/1

17

They also tried to rig the NBA All Star vote once, so there'd only be white guys on it.

18

Pool's closed.
One of the classics of the old 4chan. They made human barricades on Habbo Hotel so no one could get in the pool.