15. That one time... Dean was able to talk to animals because he kinda became a dog.
14. That one time... they were part of a Japanese Game Show. NUTCRACKAAAAAA!!!!
13. That one time... Sam and Dean ended up in a Supernatural Convention with people cosplaying them.
12. That one time... Sam and Dean found out about Wincest in slash boards.
11. That one time... They found out God had a sister and witches, demons, angels, Lucifer and God had to join forces to kill her.
10. That one time... They became cartoons and met the Scooby gang
09. That one time... They spoofed Grey's Anatomy, Knight Rider, CSI: Miami, some game shows, a Sitcom and a Genital Herpes commercial.
08. That one time... Dean ended up in a Gay BDSM Dungeon
07. That one time... They travelled to a parallel dimension in which they were actors and had to act.
06. That one time... they had to fight Demon!Gandhi and Demon!Paris Hilton.
05. That one time... There was a murdering Unicorn on the lose throwing rainbows from it's butt.
04. That one time... Dean killed (Resuscitated) Hitler.
03. That one time... They discovered Faeries had nipples.
02. That one time... They fought cartoon style. ACME style!
01. That one time... Lucifer became the President of the United States, bang'd the First Lady and got her pregnant, and then the Winchesters were arrested for attempting to kill POTUS.
Source: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
ONTD, weirdest SPN moment?