Here's the main thing:
- "'To be honest, I don't think any of the children believe he's dead,'" says Felicity [Dahl's widow]. 'I still have children coming up the lane and peering over the wall and asking if this is his house and if they can see him. I think they'd worked out that, gosh, he would have been 90, and some of them asked, 'What would he do for a party?' So it grew out of a seed of an idea that children in the UK would wear yellow (Dahl's favourite colour) or their clothes inside-out or share a book.'"
So wear some yellow, or share a book on the 13th of September. (I'm a little reluctant to suggest the inside-out strategy as it often happens inadvertently without a birthday celebration!)