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