"It's Ziggy's birthday party and everyone's invited, even Robbie Rotten. Stingy makes all kinds of excuses not to attend because he doesn't want to bring a gift."
When Robbie reads the calendar, it is seen that Sportacus' birthday is on the 10th, like his actor Magnus Scheving (10 November). Ziggy's birthday is on the 14th, like his voice actor Gudmundur Thor Karason (14 June). Also, on the calendar, there is a photo of the original Stephanie (Julianna Rose Mauriello).
This is the second time Ziggy's birthday is celebrated on the series, the first time being "Happy Brush Day."