Hole in A Cap of Ballpoint Pen
If you inspect a ballpoint pen you will not detect anything peculiar. But if you scrutinize closely you will observe that there is a minuscule aperture in the lid of a ballpoint pen. Given that ballpoint pens evaporate if they are kept without their lid on for too long a hole in the lid defeats the purpose right?
It is there to safeguard one’s existence if someone inadvertently ingests the cap. Some minors and even grown-ups have a detrimental propensity of placing pen caps in their maws and the aperture is there so that air can traverse without significant difficulties.