Okay, here's another - it's probably easy now, but when I first heard this as a child no one ever got it right...
A man is driving his son to a football match. Another car pulls out in front of them, the man swerves to avoid it, and crashes into a tree. He's okay but his son is badly injured. He takes him to casualty, saying 'please look after my son'.
When he's taken to theatre, the surgeon looks at the patient and says 'I can't operate on this patient - he's my son'. Neither the driver or the surgeon is lying. The boy is not adopted, nor does he have a stepfather. How can this be?
