be (all) dressed up like a Christmas tree

old-fashioned To be dressed or decorated very ostentatiously; to be who is particularly pretentious or showy in appearance. She was dressed up like a Christmas tree, swanning about in all her furs and jewelry. Why are you all dressed up like a Christmas tree? We're only going to the movies. I'm all dressed up like a Christmas tree because the CEO was supposed to visit our office today.