Berit Brogaard in Psychology Today:
It's the second night at the same restaurant. You order the Chilean cabernet. It's reasonably priced at $32. The waiter disappears and after what seems to be hours he comes back with a different Chilean wine—not one on the wine list. “We are out of the Chilean cabernet,” he says and decisively places the new bottle on the table. “But I can give you this exclusive Chilean blend for only $7 more. It’s an excellent bottle.” As if in a trance you quietly nod in agreement. The con artist opens and pours. Déjà vu! Except last time it was a French Syrah. This time you and your partner agreed you wouldn't spend more than around $30 on wine, yet once again you ended up with a bottle closer to $40. Sales trick or not, it’s plainly obvious that you bought right into it.
You walk into a computer store intending to purchase one of those teensy $300 notebooks for your teen daughter but walk out with a $2,300 MacBook Air. It didn't feel like a spur-of-the-moment buy. Somewhere along the way your intentions shifted, and at the time you actually thought it was a brilliant idea to reach into your pocket for an additional $2,000. You are not quite sure how it happened, and now it’s too late.