I work with adolescents. I've seen a trend to call typical changes in mood "bipolar." When I hear it it's usually used as an excuse to explain unacceptable behavior.
A couple of years ago there was a trend locally for teens to "diagnose" themselves with DID. They never saw a pdoc, just decided they had DID because of mood changes during the day.
In my experience it isn't just teens who do this. Parents of active young boys will decide the child has ADHD because he is a typical active little boy. I've been accused by co-workers of being OCD because I want my paperwork to be accurate. I'm not OCD. I just want my paperwork to be correct.