Cartman started blurting out more and more strange and personally revealing information after pretending to have Tourette's for a while. It was funny to him when he first started (though not to others who's lives he fucked with) but when he got stuck and couldn't
stop due to his inherent lack of self-control, he could no longer repress his negative or revealing feelings, and along with his new found emotional honesty, people could
see him for who he really was instead of the image he wanted them to see all the
time.