Oh man there are a LOT, but I think one that sticks out is It's a Deal by easterlystars. It's a TVXQ fic with spies doing a fake relationship. It is hilarious. Had me just busting up at some parts. It has total 2000's comedy movie energy in the BEST way.

Link: https://archiveofourown.org/works/6667894/chapters/15251053