In the movie Punch Drunk Love, the protagonist, Adam Sandler, notices the following:

“Healthy Choice and American Airlines got together and put this promotion: If you buy any 10 Healthy Choice products, they will reward you with 500 frequent flier miles; with this special coupon, they’ll up it to 1,000 miles. So, I think they are trying to push their teriyaki chicken which is $1.79, but I went to the supermarket and I looked around and I saw that they had pudding…for 25¢ a cup.. comes in packages of four. But insanely….the barcodes.. are on the individual cups! So, quarter a cup, say you bought $2.50 worth. That’s worth 500..with the coupon it’s 1,000 miles. It’s a marketing mistake but I’m taking advantage of it. If you were to spend $3,000, that would get you a million frequent flier miles. You would never have to pay for a ticket the rest of your life”

The protagonist does in fact accumulate chocolate pudding, and the resulting frequent flyer miles turns out to be a critical plot point.  According to this and this, this incident happened in real life.  Healthy Choice, by the way, is thanked in the credits.