- "Doc reached in the pocket of his lab coat and pulled out a silver bag. / 'Recognize this?' he asked. He handed the bag to Marty. 'It's the bag the Sports Book came in. I know, because the receipt was still inside.' Doc passed the receipt over, too. Yep, there it was, the name of the Antique Store, followed by the words 'PURCHASED: GRAY'S SPORTS ALMANAC 1950-2000' and the incredibly inflated price. It was the book Marty had bought, and here was the bag he had carried it away in. But Doc had thrown the book and the bag away, hadn't he?"
- —From Back to the Future Part II by Craig Shaw Gardner (quote, pages 124 and 125)
A receipt is a written acknowledgement of money or goods received.
Marty McFly received a receipt when he purchased the Grays Sports Almanac from the Blast from the Past memorabilia/antique store in Hill Valley on October 21, 2015. This was put, along with the almanac, into a silver-colored plastic bag bearing the Blast from the Past store's logo by the saleswoman.
The receipt was printed on blue paper with white print (as opposed to the more familiar white with black print), and had the Blast from the Past store's logo at the top. A barcode was printed down the left-hand side, while on the right details of the purchase were printed in computer-style text.
Emmett Brown discovered the receipt and the Blast from the Past bag in the DeLorean time machine, along with the top of Biff's cane, after he and Marty left 2015 for 1985, but instead found themselves in a nightmarish alternate reality.
- Colored cash register receipts with white print like that seen in Back to the Future Part II have yet to appear. At the moment, receipts are still printed on standard white paper with black print. Also, the use of computer-style text hasn't been adopted in real life.