I had one yesterday trying to overstay
Half hour booking and was down to the last five minutes when I told him we were running out of time.
He then decided to pop and I went to wash my hands. When I came back in the room he then wanted a "wash" which I didn't mind but then heard the bloody shower go on which I'd have said no to.

As soon as it got to the full 30 minutes I knocked on the door, told him the time and threw his t-shirt on the bathroom floor, that he'd left in the bedroom. He was only a couple of minutes over but would have stayed longer if I'd not nudged him.
Really gets my back up now when they take the piss with time.