Rich parents reserved an entire public pool just for their kid's birthday party. They obviously expect a lot of pooltoys but unfortunatly, the night after the reservation was made, all the toys that were prepared in the pool, were taken by a strong wind. Lesson for the future - prepare these toys an hour or 2 before the party, don't do it earlier.
But that's for the future, right now, we need SOMETHING to put in the pool. Lucky for the owner, some random guy didn't realise the pool was closed for the party. He shouldn't be here and the owner've been practicing some magic...