A story about how expectant mothers get to the hospital

At the bottom of our garden is a fence, and on the other side of the fence is a hospital. Here is a story the small man (3 and a half) just told me:

"At night when I'm asleep and you're asleep and mummy is asleep, ladies who have babies in their tummies put on bouncy legs and frog costumes, and they jump over our fence and land on the hospital roof. Then take off their costumes, and go into the doctors and take their babies out. Then they put their costumes back on and jump over the fence onto the shed and then off the shed and then throw the frog costumes into Valentina's garden (our neighbour) because it's hers, and then go back inside and show us their babies in the morning".