Unplug the Router
I worked at a chain pizza store. It was Saturday night, and it was busy, as Saturdays usually are. This employee took it upon himself to unplug the router, disabling the store’s internet and thus online orders without telling anyone.
When I arrived Sunday morning, the internet was out, and I spent all morning trying to fix it. Finally, we called our internet service provider, and they sent out a tech on Tuesday morning. We were without online ordering Saturday night and all of Sunday and Monday and probably lost about $3K in business.
Once the internet was back up, I was able to check the networked security cameras. I watched him unplug it and later plug it back in incorrectly.
When questioned about it, he lied, stating the cables got knocked out on accident. He was fired on Tuesday.