What Shape Is The Earth?

Teacher: What Shape Is The Earth? 
Student: I Don't Know. 

Teacher: Well! 
What Kind Of Earrings Does Your Girlfriend Wear? 
Student: Square Ones. 

Teacher: No, I Mean The Ones She Wear On Sunday. 
Student: Round 

Teacher: Then, What Shape Is The Earth? 
Student: Square On Weekdays 
And Round On Sundays. =P