Not being in possession of an imagination as fertile as LITSL, I came up with a more mundane explanation. I said that my finger was caught between a concrete fence post and some chain link fencing as the fencing was being tensioned. The boys on the ratchets couldn’t hear me because of passing trains so I pulled my hand away to avoid it being crushed, thus losing nail.
No, the boys in the office didn’t believe me either but they had something in their book in case of any comeback. I just had to change the work schedule to show that we had been fencing.