Hope its getting better Maggot...
Two for me...
Dad did cut the tip off his finger as described...he was an artist who framed his own paintings. Cutting a board with a heavy straight edge and a stanley knife, one hand pressing on the straight edge, other cutting. Sadly he didnt realise he'd left his fingertip hanging over the straight edge....to be cleanly cut off by a very sharp blade. He shoved the severed tip back on, strapped it up tight and didnt dare look for a week (he's remarkably squeemish). When he did, it was clean and almost healed perfectly.
Mine was undoing those b'stard heavy plastic cases they enclose venetian blinds in. Cutting it open with a stanley knife...struggling with the b'stard strength of the plastic...all of a sudden the knife skittered off in an instant...cutting a perfect circle out of my finger nail, just down to the pink flesh, which quickly welled up with blood. Just the depth of the nail, no more. I shouted 'B'stard..b'stard', clamped my cut finger tightly in the other hand and ran up and down the landing, blood oozing out of my tightly clamped fingers. Running ??? why ?? where ???..

I never figured that one out.
When you try and reproduce the action that would have allowed that to happen, the angles, the twists to get there'', i couldnt figure out how the hell i did it.