Excellent light-hearted approach to the subject
I found this book when my children were young (they are now grown up), thought it was great at the time, and have often highly recommended it to other parents over the years.
When sorting out books after youngest left home, I realised we were missing our copy, and thought it was such a treasure that I ordered a replacement copy.
The illustrations are never graphic, and the Mum and Dad scenes are depicted in a wonderful way. My memory is poor, but without hauling it out to confirm the exact details, I seem to recall that costumes and space hoppers are involved. Totally unrealistic in any literal sense, but kids are left with the impression that sex is something that is fun and happy that people do when they like each other.
I say it again: highly recommended.