la-di-da BrE AmE , lah-di-dah /ˌlɑː diː ˈdɑː/ adjective informal
[ Date: 1800-1900 ; Origin: Copying the speech of upper-class people ]
used to describe someone’s behaviour when you think they are talking and behaving as if they consider themselves better than other people SYN snobbish :
a la-di-da attitude