Kirst is an expression used to describe someone who pretends they have a pet cat to be cool and fit in with society.
A 'kirst' can usually be detected because they unneccarily bring up their make believe cat into a conversation. This is all part of their attempt to make their elaborate lie believable.
Girl: Wow that rainbow looks so lovely
Kirst: yes me and my cat looked at YouTube videos of rainbows last night
Girl: stop being such a kirst. I accept you without a cat!
Kirst: I do have a cat called Harvey!
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