The Title of Never Hit a Jellyfish With a Spade by Guy Browning

I was frustrated by the fact that the title of this book is never explained and there is no titular article in there, so I messaged Guy Browning on Twitter:

"Why is your book called "Never hit a jellyfish with a spade"? I keep waiting for the jellyfish reference but I haven't found it yet.

His answer: "I once asked a VIP what was the most important lesson they'd learned in life. I was looking for something helpful for my own life and it turned out, despite them, that it was. At least as a book title!"