If a user is unhappy with some of the content of the questions being asked they can choose to block certain users even if they don’t know who they are. However ask.fm does warn that even if you block a user they can still access your profile and view your interactions. The blocked button simply prevents that user from sending you questions or likes.
We recommend Internet Matters for further information about ask.fm. Access free
parental control how-to guides to get up to speed on how to set the right level of
protection to give them a fun and safe experience.