It’s Someone’s Birthday Today is a fan story written by ArthurEngine.
Krystal has gone out shopping with her mummy. She wanted a party outfit and a present. Next morning, Melanie was asleep in the bathtub, much to her daddy's surprise. Melanie finds her friends carrying brightly colored presents, meaning it's someone's birthday.
- A reference to Harry Potter was made, when Perry told Melanie "It's not everyday your young lady turns eleven now, is it?", referencing the time Rubeus Hagrid told Harold James Potter "It's not everyday your young man turns 11 now is it, eh?".
- This story is loosely based on the Little Monsters episodes, A Perfect World and Whose Birthday is it Anyway?. Krystal's shopping trip is based on the former, while Melanie trying to figure out whose birthday it is is based on the latter.
- A reference to Airplane! was made. Perry said "Surely you can't be serious!", to which Katie said she was, "And don't call me Shirley."