Irrational people can be a source of amusement after all:
Begin here:
http://www.doonesbury.com/strip/archive/2012/02/06
and click forward one page at a time through to February11th
http://www.doonesbury.com/strip/archive/2012/02/11
Now test your refurbished sense of humor:
Some people believe that "chemtrails" contain chemicals or biological agents purposely sprayed on the population by governments or other authorities.
http://contrailscience.com/
(includes good video)
Chemtrails Song:
http://www.youtube.com/watch?v=5--Iq4FPyGU
Chemtrail conspiracy theory:
http://en.wikipedia.org/wiki/Chemtrail_conspiracy_theory
http://en.wikipedia.org/wiki/List_of_conspiracy_theories#Chemtrails
Psychological Origins:
http://en.wikipedia.org/wiki/Conspiracy_theory#Psychological_origins
Examples of 'dangerous' conspiracy theories are the "International Jewish Conspiracy" and the "Holocaust Denial".