Someone holding a big sandwich is watching the World Cup at home with their family; then they bite into their sandwich, but they don't like it, saying something is missing. Then there is a bad foul in the game, and the referee shows a yellow card, at which point the sandwich person says: "That's it!" Then the person goes into the kitchen, grabs some French's mustard from the fridge, and puts some on the sandwich, after which they return to watching the game and blissfully eating their sandwich.
Then the slogan is: "Score some French's!"
(The weakness of this ad, however, is that it does allow French's competitor to claim the ad suggests French's mustard is "foul-tasting", because it could be claimed that the foul made the sandwich person think of the mustard, rather than the yellow card.)