1990:
PROM QUEEN SWEETHEART SISTER PONIES
There is something overwhelmingly American about this set, and, it will come as no surprise to most people reading this page that this was one of the North American exclusive sets for the 1990 year. Proms are a very American institution, and, although they are becoming more common now in the UK as well to mark graduation from secondary school, the idea still hadn't caught on much over here by the time these ponies were released.
That said, they could have sold them anyway, and renamed the set like they did with so many others.
Each pony in this set came with all she might need to attend her prom, except, perhaps, her Prom King. They had the classic floral earring, though were the last set of ponies sold in this slender style to have the piercing, as well as a ruffle skirt, perfume and other interesting accessories.
All of them were sold with very curly hair, which often becomes knotted, tangled or, erm, simply a big clump of, well, bunched up hair. A Prom Queen in good condition with accessories can look really pretty - one who's had a rough night on the town can look considerably less so.
Perhaps because of the accessories they were sold with, it seems difficult to find Prom Queens loose in good condition.
Someone spiked the punch, maybe.