Does anyone recognise these lines from children's books?

[Aloha]

My ds has just typed out a very bizarre but funny short story (he's 5, and it is very short!) which starts:

"Great greetings my lad!"
"I'm not important and I'm certainly not famous. Nobody know about me or who I am."

And later on

"Well, then stinky fizzy hood witch, no good witch, oh smelly-got-slugs-in-your-tummy witch"

I feel sure he must have picked up these phrases from a book, but it's not one of ours! Any ideas? I'm just curious.

I don't know, but they sound good!

I feel that 'great greetings my lad' is vaguely familiar, but no idea why.