A childhood belief about imaginary friends

I used to tell my stepkids about a friend of mine named Mr. Donkey. A donkey with seven antlers. I told them that he came over to visit when they were with their father every other weekend. My favorite story was to tell them how he'd relax in the bathtub, reading the newspaper and smoking a big cigar.

Once, I made little muddy hoof prints in the bathtub, and made some leading through the kitchen. Neither of the kids had believed a word of my stories up until then. But they became instant believers.

For about a week.