The Splurging Sturgeon is an inn and tavern in Baldur's Gate Northeast.
On the second floor, a man named Mr. Shade waits to speak to you. Doing so will cause him to take the Golden Pantaloons from you if you possess them. If not, you can engage in a meaningless conversation of innuendo that ends with his realization that you're not who he's looking for, after which he leaves.