The suggested solution I read was "I don't remember the worse party." Isn't this a very strange sentence? If you use 'the' it means there's only one (otherwise you'd use 'a'). So if there's only one that's worse, wouldn't it be the worst?
In other words, shouldn't the possible solution "I don't remember the worse party." be removed?
The default sentence has 'a worse party', so 'the' shouldn't be accepted unless you use it yourself. But Duo sometimes does not work how it should. Theoretically you could have mentioned two parties, so one is 'the better one' and the other 'the worse one'.
Having said that, we will think if this isn't indeed too weird to accept.
Then there is the, I can't remember a worse shindig, no end to what you may translate it to in America, I believe the current generation is trying to destroy the language as we were taught it in school seventy years ago. With the advent of the cellphone, the language has has steadily deteriorated into nonsensical mush.