If 'dress up party' these days literally means putting on a dress and attending a party, I weep. Dress up parties in my day were when everyone put on some cool fancy dress costume and had truckloads of cake.
Dress up parties when you were five were like that. 13 year old girls don't have dress up parties where they dress up like spiderman, they actually dressup in actual clothes.
Got here a day late.