If I had to justify Susan agreeing to this (and I do, someone's bound to comment), this is another cut scene scenario. Susan began a conversation with the wrong NPC and inadvertently started a mini-game.
There is bartender mini-game in Fable 2, and I think it was just pressing a button at the right time to slide a drink? I'm not sure. I didn't care for it, much. Maybe it was more "realistic" than finding loot on every enemy, but from a gameplay perspective, it was a terrible idea, as things were set up so you likely had to play at least one of the mini-games to get your gold going, and that's so not what the core mechanics of the overall game are.
Whatever it is you're doing most often as gameplay, that's what should get you your rewards, however silly or unrealistic it might seem to nitpickers.