A guy goes on a golfing trip to Scotland.
He turns up at the golf course and asks if someone will play golf with him.
One of the members agrees to play him the following day. " I'll be there at nine o clock but I might be 30 minutes late" says the member.
The next day they play at 9am. The member plays left-handed and soundly beats the visitor, who isn't too happy to lose.
"Will you play me again tomorrow?", he asks.
"OK" says the member, "I'll see you at 9am again but I might be 30 minutes late".
The next morning they play at 9am and the member wins again, this time playing right- handed.
"Will you give me one more chance to beat you?" asks the visitor.
"OK" says the member. "9am tomorrow but I might be 30 minutes late".
"Hold on a minute", says the visitor, "yesterday you play left- handed, today you play right-handed. How do you decide which way to play?"
"Well", says the member, "when I wake up in the morning, I look at my wife lying in bed. If she's lying on her left side, I play left-handed. If she's lying on her right-side, I play right-handed".
"What if she's lying on her back?"
"I'll be 30 minutes late"