I never used 4chan but I sometimes see screenshots of their posts, and the funniest quote I saw from one of their users is "4chan is a bunch of smart people pretending to be retarded, Reddit is a bunch of retards pretending to be smart".

Remember when they located the Boston bomber, and the guy they tried to pin as the bomber was someone who was dead for months before the attack? And reddit even went on to dox the dead guys family? Wow. 4chan once located a terrorist base in Syria based on the background of one of their propaganda videos, managed to communicate this information to a Russian military leader, and the next day the base was blown to bits by missiles.