I had a bad headache at work yesterday and it's clear mistakes are made when distracted. In this case I was running digested vector and DNA out on a gel to purify them. When I looked at the samples there didn't seem to be a band for the DNA in my vector digest so i threw it in the ethidium bromide cookie jar. Then I realised an empty vector wouldn't have the DNA in as that's what I was attempting to make. So i fished the gel back out the trash (don't worry it was at the very top) and cut out the digested vector bands.
I then decided to take a lunch break in the hope my head would clear up.
The headache didn't clear up but, when I got around to the ligation, I realised I should have cut another two bands out of the gel as well. There was no going back to that gel as I had already eviscerated it.
Guess I'll be repeating that one again. My headache seems to have gone so any additional cock-ups are solely due to ineptitude.