Alt tabbed one too many times, clicked drop database, clicked ok, realized I’d just deleted the live user database for America’s Army. Thankfully it was the east coast site and west coast was the primary, and it was only one way replication. We shut down east coast auth and rebuilt the secondary.
Someone distracted me while typing in a vlan command on a switch, I hit enter without double checking, took out our fiber between two datacenters in the middle of a move. Took me 15 minutes to run to the DC, plug in a console cable and fix it. Took all of our customers out.