Silliest thing I have done???? There are so many!
I told you a couple of weeks ago of spending ages getting the washing sorted, because the control button was playing up a bit, measured in the powder etc etc, set it going and only discovered the laundry basket with the washing still in it half an hour later! I bet my machine was nice and clean though!
Incident where I felt most stupid happened many years ago, when the children were about 10. We'd been on a camping (not real camping - one of those where the tent is all ready for you etc etc) holiday in France. The dates were from end July to early August. You know how you lose track of days when you're on holiday?..............well, after our 4 hour drive back to the ferry at St Malo they looked at our ticket and said 'but why are you here today, this is for tomorrow!
All down to me, I did the booking etc, just 'forgot' 31 days in July, not 30! Anyway, we waited till just before sailing and they squeezed us in - literally. Inches to spare all round!