Using a dupe hammer to close asa question as a duplicate and using it again to reopen when the user explained how it wasn't actually a duplicate.
Casting an incorrect spam flag when seeing a report in the Charcoal HQ chat room. When I was told by other room participants that my flag was incorrect I retracted the flag (this is a new feature - flags can now be retracted if they haven't been actioned).
replaced http://meta.stackexchange.com/ with https://meta.stackexchange.com/