If you’re not familiar with the term FIFO, it stands for First In, First Out. An asset-management and valuation method in which the assets produced or acquired first are sold, used or disposed of first. For example, if you buy the same stock on different days, then sell some of that stock later, the profit/loss is based on the first set of shares you bought. The first ones you sell will be removed from the first ones you bought.
Well, as it applies to teeth, it just so happens that the first two teeth JD got when he was 4 months old, are the first two teeth he’s lost. The second was extracted by the boy himself just an hour ago. I’m a little weepy over it.