A person who becomes a vegetarian simply because it is trendy to do so. These people do not have any moral opposition to eating meat, they are just trying to be "hip".
Girl 1."Natasha had decided that she's not going to eat meat anymore"
Girl 2. "Why? Because she doesn't believe in cruelty to animals? Or is it for environmental reasons?"
Girl 1: "No it's not like that, she's just being a trendyveg."