Which "Hidden Purposes" of Everyday Things Are Real?

The hole in your pen cap, the squares on your toothpaste tube, the lines on a party cup: viral videos say they all have secret purposes. We checked ten of them for a paper trail. Some are genius, some are made up. In about 11 minutes: -The safety standard behind the hole in your pen cap -The "ingredient code" on toothpaste and the party cup "bartender's guide," checked -Why airplane windows have a tiny hole, and why your tape measure wobbles on purpose -The Ford designer who pulled up on the wrong side of the pump and fixed it for everyone Sources: ISO 11540 (caps for writing instruments); BIC FAQ via IFLScience; Snopes Mental Floss, toothpaste color codes; Colgate, "What Is a Toothpaste Color Code?" Levi Strauss & Co., "Pockets Full of History"; Encyclopaedia Britannica, "Why Do Jeans Have That Tiny Pocket?" PolitiFact (2019), Solo cup lines; Snopes; NIAAA, "What is a standard drink?" Snopes, holes in pasta spoons; Molly Maid Canada Gizmodo (2015), "Why Is There a Hole in Airplane Windows?"; ScienceAlert Associated Press, "A humble oyster pail turned takeout icon"; South China Morning Post Gear Patrol, Mental Floss and VinePair on wine bottle punts The Drive (2026), "The 'Moylan Arrow'"; Design News, "How Your Car Got Its Fuel Fill Arrow" This Old House, "What Makes It Wiggle"; Mental Floss; US Patent 4,466,194 Chapters 0:00 Let's check 0:37 The pen cap hole 1:29 The toothpaste squares 2:23 The tiny jeans pocket 3:17 The party cup lines 4:14 The spaghetti spoon 5:12 The airplane window hole 6:08 The takeout box plate 7:09 The dent in wine bottles 8:04 The fuel gauge arrow 9:05 The wobbly tape measure