It is a big thing here, with all of the formal dances. DS18 was a Senior last year and his girlfriend specifically said she did NOT want a big, elaborate, public invitation. That made it easy. She still wanted to be invited. Nice that she made it all so clear

So he invited her in private, with flowers. Perfect for who she was.
In November we came home from having dinner out, to find a girl in front of our house with a poster board, and she was covered in blood

She was here to invite DS16 to her Winter Formal. It was the night of the first Walking Dead for the season, and they both watch that show. So she was dressed up like a zombie, and the poster said, "I came back from the Dead to ask you to Winter Formal." Then she had Yes and No boxes for him to check. He was not dating this girl and had never even thought of it as a possibility that she would ask him. Poor kid was in shock. Breathing super hard before he got out of our car...saying "what should I do?!" I told him to take a deep breathe, make a decision, and go out there and see her! He checked yes and they had a nice time at the dance. She is a year older, our HS is divided into 9-10, 11-12, so this dance was for her school not his.
DS16s Snowball Dance was in January. So a few weeks after going to Winter Formal with Zombie Girl, it was time for him to invite someone to Snowball! He invited a different girl. He and this girl had gone on a few dates and she was not surprised that he invited her. She said yes. He went to her house with a vintage vinyl Credence Clearwater Revival Album. He put a note on the front of it that said, "It would ROCK if you went to Snowball with me." She LOVED it. He took a red rose too. Not public, but certainly instagramable.
I've seen PROM? on cars, lockers, and windows of houses lately. Tis the season!