The children had gone to bed, it was 8:30pm but sometimes DD can take ages to settle and if disturbed can be up till early hours of the morning. thankfully she settled off pretty quickly.
We (DP and I) had just poured a glass of wine and was gonna watch a film when DP had a text of our neighbour to collect some disc for the laptop or something or other he had for him as it was ready. The last thing i said to DP was "make sure you take your key!!" (he was only gonna be a few mins but not to disturb DD)
10 mins later a knock on the front door, Dog starts barking making a right racket, wakes DD who starts screaming furiously in her cot, and i'm stomping down our passageway in the dark shouting "why can you never remember your bloody key!!!!!??????" opened the front door, and standing there was our pastor from Church! 
when i seen him the following sunday i apologised for shouting at him (whilst my cheeks got redder and redder) and he laughed and said "its ok i'm just glad that i saved (DP) from having a row!"
i felt rather embarrassed
That'll teach me not to assume who's at the front door! (its just that we never really get visitors after 6:00pm as they know we'll be getting the kids ready!)
hope my oops moment brightened up your evenings all!