Here is the full list of all 20 Oh...Sir! The Hollywood Roast achievements worth 1,000 gamerscore.
Win your first argument
Finish the basic tutorial
Take 30 Pride points off your opponent with a single insult as a Single Star
Win a Roast losing less than half of your HP
Use 3 Comebacks in one single player fight.
Use a 55 points hot burn playing as a Single Star
Win a Cliffhanger
Win a Roast in less than 3:40 minutes
Prove victorious in a battle royale of CFOs
Receive 15 Golden Parrots with one character
Receive 69 Golden Parrots in total
Have 3 characters receive 15 Golden Parrots each
Have 6 characters receive 15 Golden Parrots each
Finish the career as Dirty Potter
Finish the career as The Greasy Wizard
Finish the career as Chop Sue E.
Finish the career as Marilyn Nomore
Finish the career as Wisecrack
Finish at least 25 scenes online
Finish at least 65 scenes online