Q: Why did the golfer wear two pairs of pants?
A: In case he got a hole in one!

Explanation: I have never been golfing but this joke made me laugh. 

Pants are an item of clothing that you put on one leg at a time.  They are also known as slacks and trousers.  Jeans are pants.  Although some people like to have holes in their pants, most people do not like it when they get a hole in a pair of pants.  If you get a hole in one pair of pants, you might want to put on another pair of pants without a hole.

In golf, a hole-in-one means that you got the little white ball into the hole with just one swing of your golf club.  I understand that it is hard to get a hole-in-one while playing golf.

This joke is funny because it plays with the meanings of “hole in one.”

Here are some famous golfers getting a hole-in-one.