Lagoona and Spectra introduce Sirena Von Boo to two new howlidays—New Tide’s Eve and Chainsgiving—celebrating her fusion scaritage.
Spectra meets Lagoona and Sirena in a corridor, where Lagoona is about to ask Sirena if she's excited for New Tide's Eve. Sirena states that she doesn't know what New Tide's Eve is, which confuses Lagoona, since all mermaids celebrate it. Sirena explains that since she's a Hybrid, her parents decided not to force her to choose one of their scaritages over the other.
Lagoona explains that New Tide's Eve is a popular holiday for mermaids, where they play the sport of Finball and go dancing underwater. Sirena admits that it does sound fun. Manny stops by to point out that minotaurs have an even better holiday: Minotaurial Day, where they spend the day headbutting each other. Despite that, Sirena decides that New Tide's Eve sounds better.
Spectra notes that it reminds her of Chainsgiving, a holiday for ghosts where they decorate a tree with lights, attempt to break a pinata, and have a huge feast. Sirena is delighted that she has two great holidays she can celebrate, and Lagoona and Spectra invite her to join them in their respective celebrations. There's only one problem: Both of them take place on the same night. Both Lagoona and Spectra graciously suggest Sirena join in the other's celebration.
That night, Lagoona and Spectra are waiting outside the school for Sirena, but there's no sign of her. They search inside the school, and find Sirena in the swimming pool, where she has a surprise for them. She reveals she has combined the New Tide's Eve and Chainsgiving festivities into one party, with a finball court set up in the pool and a Chainsgiving tree set in the middle. This way, they can all celebrate together. The ghouls immediately dive in and start having fun.
- The name of the webisode is a play on the saying 'Happy Holidays.' In which Chainsgiving and New Tides Eve are Thanksgiving and New Years Eve are respectively based on.
- The Holiday Manny mentioned is a play on Memorial Day.
- If Chainsgiving is based on Thanksgiving and New Tides Eve is New Years Eve, both holidays couldn't occur in the same day.