"Birthdays Are Forever" is an episode of Special Agent Oso.
While Oso tries fixing the air brakes on his special agent train, he fails and switches the tracks and causes Rapide to fall into a lake and gets a special assignment to help a boy named Quinn make a party hat for his birthday photo, but he gave the last party hat to his baby cousin named Madison. So Oso decides to help him make the party hat so he can get a picture of himself wearing it.
- The episode's title is a reference to the James Bond film Diamonds Are Forever.
- Birthdays Are Forever is a continuation of The Boy with the Golden Gift because of Quinn's birthday being a plot element of both episodes.