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