I've done something (unintentionally) that I won't forget any time soon...
Okay, it was maybe a year ago, and my mother was taking my brother to a friends house, so my step brother and I were all alone in the house. I was trying to find a number, so I punched in '411' on the phone, but it just so happens that I actually punched in '911'. I didn't notice this, however until a lady picked up, and informed me that I was talking to someone in the Police Station.
Not thinking, I hung up. They called back, however, and told me that they were going to send an officer to my house to check out the problem. Now, it just so happens that my parent arrived at the same exact time as the police officer did, and that caused some confusion. At least the officer was nice about it. He let me off with a warning to be more careful when dialing numbers, and he was off. My mom had a laugh about it (to my relief), and...well...that's about it.
So, it's not really a 'little bad thing' I did; just a stupid mistake. :)