Day in loo

Similar to an unauthorised day in lieu, where one spends the day in a work cubicle playing phone games, searching for porn and thinking about urban dictionary definitions.

Boss: 'Are you taking another day in loo then, David?'
David: 'How'd you know, Boss?'
Boss: 'Partly because you missed the big meeting, but mainly cause you're absolutely covered in jizz, you reprobate'