People who drive excessively large cars when they only use their vehicle for commuting and errands (there are valid reasons for owning a larger car, such as being disabled or being a handyman character who moves lots of shit around, but these reasons do not apply to the overwhelming majority of people).
There's rarely a valid reason for owning a large car- people think it's normal to sink huge sums of money into cars, just because they think they are impressing people that they don't even like.
Some people sit in their cars with the engine running. Why? The AA and RAC have advised this damages the car's engine, and that car engines should be switched off when vehicles are stationary. So why leave the engine running?
Personalised number plates. Or people putting that stupid plane wing on the back of their car. Getting "twat" tattooed across your forehead would achieve the same thing.
Lying sprawled out on the grass, or on a beach, on hot days. This quite literally serves no purpose. It is something that people only do because they have seen other people doing it.
Men taking photographs of themselves. I'm ugly. Most men are ugly. Taking a photograph of yourself doesn't change that.
The really weird duckface pouty-lip facial expression that people do in photographs. This one is disgusting.
Seeing dozens and dozens of men flocking to a woman's photographs on social media and all of them telling her how wonderful she is. Cringe.
People listening to shit and generic music in the charts just because everyone else listens to it, and they think that's what they are supposed to like. There's nothing wrong with liking different music.