When someone doesn't agree with your opinion anymore and just shuts you down and, basically, tells you to go fuck yourself for being an individual. It usually makes you spend the weekend feeling bad about yourself.
Casey didn't want to hear anymore about my thoughts on his favorite football team so he said "On a serious note, I'm out having fun and having a good time, you're really not being cool and pissing me off just leave me alone while they play." and, upon trying to express your opinion of a tv show says "oh, shut UP, I can't deal with this" and then you feel bad inside for having tried to be a part of his life. It was all extraordinarily dismissive.
The refusal to acknowledge the professional acumen of an ethnicity other than one's own, based on a stereotype and position that one's racial/ethnic background is superior.
Ex 1: The intellectual ethno-dismissiveness (IED Complex)of voters who discredit the validity of President Barack Obama's abilities in office, fueled the Tea-Party movement.
Ex 2: A minority expert in his or her field is questioned or double-checked on findings. Meanwhile, the response of someone who fits the challenger's idea of "the expert" may have little or no experience, but is respected and accepted with few questions.