The Story: As a kid, my grandfather occasionally would take my brother and I to a local card, coin, & stamp shop.
A pack of Upper Deck was in my price range, so I asked to see the box. Having recently discovered the existence of relic cards, I compared the packs in my hand, hoping to find the heaviest one.
The shop owner, and my grandfather, thought I was being silly and there was no way my jittery adolescent hands could tell the miniscule difference between the pack weights.
The look on their faces when I pulled this card, priceless.
(I was never allowed to compare packs so thoroughly in the store again)