Our resident vampire wants to impress some mortals in a meaningless contest -- showing off at basketball, or something equally low-end that doesn't require his full capability.

If it's a meaningless contest, I would just say "Yes, you impress them with your awesome basketball speed. Tell me how that looks." No hunger.

If they wanted to put an aspect on the scene or on one of the mortals, like "Impressed with my dude's skillz." I'd ask them to tag an aspect for effect and pay a Fate point. Still no hunger.

White Court Vampires shouldn't get hungry playing basketball.

Morgan and I are playing in a game at the moment and there's been plenty of room for both his Wizard and my Sorcerer, with no one's toes getting stepped on and neither one of us outshining the other. Of course, he did unleash a mini-sun to save us from a bunch of Red Court Vampires and drive off their warlord, the Blood Madonna. But, then I got to slam the turncoat warden who was chasing us into a wall accidentally causing a 5.2 earthquake in the subway station under Pershing Square. So, things seem to even out.