be dressed up
phrasal verbdress up (as somebody/something) | be dressed up (as somebody/something)
to put on special clothes, especially to pretend to be somebody/something different 装扮;乔装打扮 Kids love dressing up. 孩子们都喜欢装扮成别人玩儿。 The boys were all dressed up as pirates. 这些男孩子都装扮成了海盗。 - (British English)
dressing-up clothes 化装服 - (North American English)
dress-up clothes 化装服