This is the joke from a internet friend.
Her father-in-law told her husband (school age)to help her husband dealing with his exam anxiety:

"There were two bulls walking along the foot of the hill then they saw a group of cows on the top of the hill. One bull said to the other: Let’s run up to the hill and F*** a couple of them! The other answered: why not we WALK up to the hill and F*** them all?"

Thereafter her husband achieved academic success.