The description for the "SO Goes Flapper" hat says:
post an answer with fewer than 600 characters that gets accepted while there is a competing answer with more than 600 characters
But, it feels like there are some unspecified pre-conditions for this hat to trigger:
- is there a restriction that the existing answer with more than 600 characters has to be from a different user?
- could the author of the question be the same user as well?
- does the question or/and the competing answer have to be posted during WB?