When you buy something expensive, only to find the price was greatly reduced soon after you bought it.
John: "How come mike hasn't come out recently? Last time I saw him he was crying, and contemplating self harm."
Dan : "Dawg he has PTSD. He bought the latest series of Dragon Ball Z last month, but the price got halved the day after he opened it."
John: "Oh I see. Post traumatic Sale disorder. That sucks man, he's probably too sour now too lend me it."