A fisherman is sorting through his catch on the edge of a lake when a man sprints up to him, obviously in some distress.

‘Help me please,’ he gasps. ‘My wife is drowning and I can't swim.’ He points out to a distant figure, splashing around pathetically 100m from the shore. ‘Please save her. I'll give you a hundred quid if you do.’

Nodding, the fisherman dives into the water. In a few powerful strokes, he reached the woman, puts his arm around her, and swims back to shore.

Depositing her at the feet of the man, he looks up at him. ‘Okay,’ he says, regaining his breath, ‘where's my hundred?’

The man frowns back at him. ‘Look,’ he says. ‘When I saw her going down for the third time, I thought it was my wife. But this is my mother-in-law.’

The fisherman reached into his pocket. ‘Just my luck,’ he says. ‘How much do I owe you?’