"Party favours" in not a term in use in Australia as far as I can ascertain, and I had never heard of them (with either of the meanings I discovered).
Doesn't help much when the urban dictionary definition is essentially 'hard(er) drugs'!
Luckily, overseas sites advertising other 'party favours' gave a different insight, as did wordreference.
https://www.urbandictionary.com/define.php?term=party%20favours
https://french.kwiziq.com/my-languages/french/exercises/overview/1291
