What's the description of user 85981819's movie list with the most followers?
user 85981819 refers to user_id = 85981819; most followers refers to Max(list_followers); description refers to list_descriptions;
SELECT T1.list_description FROM lists AS T1 INNER JOIN lists_users AS T2 ON T1.list_id = T2.list_id AND T1.user_id = T2.user_id WHERE T1.user_id = 85981819 ORDER BY T1.list_followers DESC LIMIT 1