The chimichanga thing started in Cable & Deadpool #13:
"Deadpool started saying chimichanga in Cable & Deadpool because he liked the way it sounded.

Daniel Way took it too far by basically making it his catch phrase during his run and a bunch of fan art followed with Deadpool loving chimichangas, burritos, tacos, etc."

In fact I have a Deadpool shirt with him yelling Tacos! It's been in the zeitgeist long before the pin.

Sauron has always been a foe to the X-men, don't think he's actually met Deadpool in comics, that is until this year: https://www.cbr.com/deadpool-sauron-dinosaur-meme-king-in-black/