Original ending of the quote "Do not meddle in the affairs of dragons"

I have seen T-Shirts and bumper stickers with the following phrase on them:

“Do not meddle in the affairs of Dragons, for you are crunchy and taste good with ketchup!”

Is this an altered version of some other phrase or has it always existed in this form?

It’s a paraphrase of a line from Tolkien:

“Do not meddle in the affairs of Wizards, for they are subtle and quick to anger.”

There was also an old cartoon with a dragon sitting in a pile of armor, picking his teeth with a lance, captioned “The dragon doesn’t always lose”.

I became aware of it in the early 80s when it was given to us as a ‘coloring page’ from our local printshop.

My version runs thusly:

“Meddle not in the affairs of dragons, for you are crunchy when fried and good with ketchup.”

And of course there’s the version i know which runs thusly:

“Do not meddle with cats for they are subtle and will piss on your keyboard”

One I remember from a Roguelike I used to play:

“Do not meddle in the affairs of wizards. It makes them soggy and hard to light.”

Of course, the best version is Pratchett’s:

“Do not meddle in the affairs of wizards, especially simian ones. They aren’t that subtle.”

Also mentioned is: “Go not to the Elves for advice, for they will tell you both yes and no.”

As a matter of giving an accurate answer, Alessan has it.

But there are rumours that Tolkien cadged it from a Sicilian original: