Here is the full list of all 18 Oh...Sir!! The Insult Simulator achievements.
Mention Satan 66 times.
Compose a phrase with "Your hovercraft is full of eels".
Compose a phrase with "Your beloved auntie worked with the Nazis".
Compose a phrase with "You still use Windows Vista and never watched Star Wars".
Play more than 100 duels.
Compose a phrase with "Your son died because of your sins!".
Compose a phrase with "Your wife is interested in photography, nudge nudge!".
Unlock a secret character.
Compose a phrase with "Your country is not a part of Europe".
Compose a phrase with "You are silly, and everybody knows that!".
Compose a phrase with "Your mother was a hamster".
Compose a phrase with "A duck hunter probably murdered this poor man".
Compose a phrase with "Your mother is your father".
Complete the Insulting Tournament.
Unlock two additional characters.
Play the basic tutorial.
Win your first argument.
Take 50 honour points off your opponent in a single insult.