When I started to watch this I really was thinking why??? but by the end you get it.

Fast-food chains spend a fortune on artists to make their food look as good as possible in ads.  So this might be the first fast-food ad ever that intentionally makes the food look as yucky as possible.

Burger King's latest ad shows a time-lapse video of a Whopper growing mold.

Burger King/YouTube

That's the whole ad.  It's a Whopper on a platform in front of a black background.  And as it speeds through 34 days, you see the burger grow all sorts of mold in different colors.

Why would they do this?  Well, there have been some pretty famous examples of McDonald's burgers lasting for years without getting moldy because of all their artificial preservatives.  And Burger King has been phasing those preservatives out of its food.

Buzzfeed mulitplayer/YouTube
They say that by the end of the year, every Whopper will be totally free of all artificial preservatives, colors, and flavors . . . and Whoppers will grow mold like other fresh foods.

So this commercial is promoting Burger King's food by showing JUST how repulsive it'll be if you leave it sitting out for a month.  It's not the most traditional ad, but it's definitely unique.