I had read this first in a set of books when I was young like 10 or something, that was the early 90s I think. I am currently looking for these set of books, I think they are out of print, this saddens me.
If anyone knows the books in question when I might buy them, please contact me.
Some of the best knock knocks and riddles ever written found in those books.
Sorry to leave such a long reply.
Thanks for your time.