Haha. It actually happened to me!
I advertised a night turn for a layover and another pilot sent me an sms a few days later. He had a highly sought after Europe layover he wanted to trade me for my night turn. I told him I'd accept it if he could put it through because I was out for dinner(the swap was legal)
I got home, checked the loads, they were open so the wife called her boss to get a few days off to go with. I sent the guy a text the next day and asked if he had a chance to send in the swap.
"Sorry mate, a better swap came through for me"
Total ******.