I always found people who take pictures with the middle finger as a trashy gesture. I don’t and never know who they’re trying to tell off but it’s out of no where and just stupid. It doesn’t offend me, I just find it a pointless gesture and therefore - trashy.
I think of trashy as the opposite end of the spectrum from classy.
Respecting others privacy and being gracious when someone is embarrassed? Classy. Arguing in front of others or loudly reprimanding someone in public? Trashy.
Dressed appropriately for the venue and audience? Classy. Booty shorts and flip flops in an office space? Trashy.
Being on time and considerate in your manner of arrival? Classy Being late and disruptive? Trashy.
You don’t have to be rich to be classy, just considerate. In the same way, people of means can be trashy if they’re inconsiderate of others.
I think to me, the ultimate trashy move is to pee in public.