don't you dare!

don't you dare

An emphatic way to tell someone not to do something. Don't you dare say something vulgar like that to your mother! Don't you dare touch that autographed baseball—it's worth a lot of money!
See also: dare

don’t you ˈdare (do something)!

(spoken) used to tell somebody strongly not to do something: ‘I’ll tell her about it.’ ‘Don’t you dare!’Don’t you dare say anything to anybody.