I might go for some cake

 It was a practical session in the psychology class.

The professor showed a large cage with a male rat in it:

The rat was in the middle of the cage.

Then, the professor put a piece of cake on one side and put a female rat on the other side.

The male rat ran towards the cake and ate it.

Then, the professor changed the cake and replaced it with some bread.

The male rat again ran towards the bread.

This experiment went on with the professor changing the food every time.

And, every time, the male rat ran towards the food item and never towards the female rat.

Professor asked the students.

“This experiment shows that food is the greatest strength and attraction, do you agree?”

Then, one of the students from the back rows said.

“Sir, why don’t you change the female rat? This one might be his wife!”

The professor stood straight up, his finger pointing towards the student and said….

“You just got an A”.