This has totally happened to me before! My sim was working on her essay on the communal computer in the hall of her Britechester dorm, and this random chick went up to her and serenaded her like that. My sim was super focused on her task at hand, though, so she kind of semi-ignored the girl by continuing her typing. I was suprised this happened too! The thing is, I'm pretty sure I saw that same chick serenading this man another day in the same way, so I don't know what to make of the whole interaction either. Either way, it made me happy I chose dorm living instead of staying at home, for sure.