Their job isn't to check up on somebody and see if they are making terrible jokes or not, their job is to make sure nobody violates the rules which you did.
"I was kidding" will not get you out of punishment because they can not tell if you really are or not, what they can tell is you were advertising to sell your account.
I would advise you don't do something in violation of the rules whether it is a joke or not because it will not be seen as a joke.