Well, Miss Carter, that would be meat.  From a billboard.

Commuters in Mooresville, North Carolina are being treated to the smell of barbeque while heading to work.  The grocery store Bloom has introduced a billboard that smells like meat, and as you can see above is shaped like a giant piece of steak on a fork.  It produces the BBQ smell with the help of a high-powered fan that blows air over cartridges packed with BBQ fragrance oil.  Blooms plans to continue the smelly ad campaign until next week.

Source:  MetroSource