Ovens "big enough for a Christmas turkey".
Freezers "with enough room so you always have food for unexpected guests".
Just two examples of clever marketing, using extreme events (once a year Christmas and let's say twice a year unexpected dinner guests) with latent cultural and social stigma's that still work on the (post)modern human beings decision making proces.
In each case they were used to sell us more. But the principle can also be used to change behaviour towards sustainability.
So ask yourself: what extreme situations with cultural resonance, and the possibility for social failure do you have within your particular business?
These types of situations and this type of approach will allow you to change behaviour by make the unlikely (yet when it happens very socialy uncomfortable) become a focus point, thus making acceptance of the new behaviour seem obvious.
Perhaps a bit evil, but given the fact it worked the first time around, I am betting it would work again.