hall pass

noun2

1. •
   (US) A permit to be out of class during school hours.
2. •
   (informal) An agreement to temporarily or conditionally relax monogamy in a relationship.

   • The story kicks in when a relationship guru (Joy Behar) suggests that the wives give their husbands a week off from marriage — a hall pass — which, after not much anguish, they do. — 2011