Here is the full list of all 12 Karen: An Outrage Simulator achievements.
Spoke with the manager, and destroyed him
Throw a tantrum at the Starcups
Expiry dates are just suggestions
You are now Karen
Lose your cool at the Con-Mart
True serenity, through the misery of others
Go ballistic at the spa
Nobody's having a good time if you aren't
Rage at the restaurant
Nobody tells you what to do
Erupt at the grocery store
You have reached the ultimate form