'notch' itself is just an indentation or incision on an edge or surface.
It is the 'something' which is the important thing here! -when you 'make a notch'.........why?
We might make a notch on something in order to keep a score or record.
Gunfighters in the Old West were reputedly known to put a notch on the handle of their guns for each person they shot dead.
So - a notch on a bedpost..... what is the person keeping score of? And just where is he going to put the notch? On his actual 'male member'? (Icon for 'ouch')
What sort of very odd person puts a notch in their bedpost to keep track of their bedtime reading? I may be odd, but if manifested that way, I'd be sleeping in sawdust.
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