Alternate History

• After a giant meteor strikes the Earth and fills the air with unbreathable iridium, the dinosaurs realize that their only hope to stay alive is to fast and hold their breaths for the next 10 years. Their plan works flawlessly. During the celebration that follows, they all jump into the pool mere minutes after eating barbeque. None survive.
• Due to a communication breakdown, the Great Wall of China is constructed 4,000 miles tall and 35 feet long instead of 35 feet tall and 4,000 miles long. Mongols completely overrun China within the year, but many perish in their treacherous trek up the wall.
• Inspired by a large upswing in his approval rating after the famous incident in which he was shot but completed the speech he was giving, cunning president Teddy Roosevelt convinces members of the secret service to open fire upon him at the beginning of every speech from that day forward. He is subsequently shot 374 times over his sixteen year term in office, and dies with only one month left to serve due to a baffling case of Sudden Infant Death Syndrome.
• While working on the theory of relativity, Albert Einstein stumbles upon concrete mathematical proof that it's okay to pork your cousin.

See the rest of the timeline at Something Awful.