Dale and Deb were friends of Marnie.
Overview
For Marnie's birthday, the couple intended to prepare her a buffet, but Marnie's husband later informed them that Marnie wanted to have an orgy with friends, and they agreed to it, despite feeling nervous about it, because of YOLO (You only live once).
The two excitedly told Marnie of their new arrangements, unaware that Marnie was possessed by Crowley, and promptly celebrated her birthday. They were killed afterwards, along with Marnie's husband.