I was recording songs for a client’s band.

Me: It takes about an hour to record a song.

Client: Great!

The band showed up for their 7 PM appointment with five songs they wanted to record. It took five hours. When we finished the fifth, though, the client decided he wanted to record one more.

Once that was finished, the band started packing up.

Client: What time is it?

Me: 1 AM. So you owe us for six hours.

Client: What? I only brought enough money for two hours!

Me: I suggest you take that and buy a watch because you just wasted six hours of all of our time.

Source: Clients from Hell