What sort of manager exactly...?

A friend called me, it sounded urgent. He'd been offered a job with a small chain of music stores as a fill-in store manager for when the other guys were away, training/sickness/vacation, that sort of thing. So far so boring. But what made his ears prick up, and made him so keen to call me, was the job title. What sort of manager? A "relief manager". There are only a small number of people who would think this is funny, and he and I know each other very well. We were hysterical. (See also back in April on here, "relief event". The way I see it, there's almost nothing that can't be turned into something agreeably smutty.)