I'm sure I'll find it in the last place that I end up looking.
I like buying refurbished IBM Thinkpads for my daily work laptops; they are reliable machines, I usually get three to four years out of a refurb, and they all use the same power adapter.
The advantage of this, for me, is that I know have "extra" adapters. I keep one by my bedside, two at my office desk, one at City Hall, and one portable. (One of my Thinkpads primarily sits at my desk as my Linux machine).
Somepoint Friday or Saturday morning, I forgot or misplaced one of the adapters.
Just writing this, I realize I probably forgot it at the local cafe. Time to go there and see if that's the case!