cock-a-hoop /ˌkɒk ə ˈhuːp $ ˌkɑːk-/ BrE AmE adjective [not before noun] British English
[ Date: 1600-1700 ; Origin: set the cock on the hoop 'to celebrate' (16-17 centuries) ]
pleased and excited about something, especially something you have done
cock-a-hoop at/about/over
Robert’s cock-a-hoop about his new job.