We have an active thread about small things you did that were money savers, but this is the opposite question: What did you do that was wasteful?
I did something stupid recently: Somehow I skipped paying the January power bill. I can't find it, so perhaps I never received it, or -- more likely -- it was lost in the house. Perhaps thrown away or put into the tax files. Anyway, I didn't pay it, so now I have TWO huge winter power bills . . . and a late fee.
Bummer, but it is my own fault. I was probably careless with the original bill, and when paying the other bills, I should have noticed that this one was missing.