The Rite of AshkEnte. When Galder Weatherwax first suggests it, instead of the "No, no, not that!" response he was expecting, the other wizards simply go, "Sure, why not?" Then when they summon Death, the reaper has a cocktail ("I was at a party."). Finally, after some exposition (During which Death refuses to go along with Weatherwax's attempts at drama), Death is allowed to leave;
Weatherwax: I hope it is a good party.
Death: At the moment it is. I think it might go downhill very quickly at midnight.
Death: That's when they think I'll be taking my mask off.