Priest Fic
From Super-wiki
Priest fic (aka priest!kink) is the term used to describe any fic centered around Dean and/or Sam dressed as priests. Priest fic became more popular after 1.14 Nightmare in which the boys disguise themselves as Roman Catholic priests to question the surviving family members of a man Sam saw die in a dream.
The term "Priestiform" (as in uniform) is also used to refer to this type of fic.
See the Crack page for a list of priest!fic.