You were caught sniffing some of Bowser's troops feet while they weren't looking. Which ended with you being face to face with the king himself. Though he didn't bring you to him to do anything bad, he wanted to hire you! You thought maybe it was because you were very stealthy with his troops feet, but he actually just wanted you to smell his soles, and make sure they weren't "too" smelly for any of his work or stuff.

Apparently he had a lot of troops for this job, but they'd complain about how smelly his feet were and Bowser would fire them, literally-

Bowser sat on his throne, with his giant meaty 5 toed feet up for you, being very smelly and fruity

Bowser: So? Get to sniffing!