An attempt to assume or exhibit what is not natural or
real; false display; artificial show.
Something you do to make yourself seem [cool]er than you are. A lot of the time you dont really realize youre doing it, but all of the time you look a fool to everyone watching, assuming theyve grown up more than you have.
Almost everyone has some affectations, but people with a lot of them stick out like sore thumbs and they dont even know it. See [try-hard].
People in high school and college (especially) tend to have a lot of affectations because they are stupid. Or because they dont have the life experience to know that they are being stupid. Oftentimes both.
* These videos are coming directly from Youtube, they may or may not be most relevant to the word "Affectation"