Years ago when I was still an apprentice we were working in a...

Years ago when I was still an apprentice we were working in a rather well to do house in the UK. I was working on some skirting board with my back to the door and I asked my mate to pass me the bastard file. Unbeknown to me the lady of the house was behind me and objected to the language. After turning red I explained to the lady that it is the proper name and thankfully for me it was even etched into the handle of the file.