Definition

Someone who spends an inordinate amount of time in the bathroom engaged in extended bathroom sessions, either for legitimate digestive reasons or as an escape tactic from social interaction.

Example Usage

Kevin disappeared for like 45 minutes at the party—that guy's the shitmeister of our friend group.

Source: Urban Dictionary (https://www.urbandictionary.com/define.php?term=shitmeister&defid=1646313)