Teacher: 2 aur 2 char hote hai to yeah batao ki mere ghar ki tanki me kitna pani hai ?
student:(to himself) yeh kya question hai?
then he says: madam the answer is 80 ltrs.
teacher: u are right! tumhe kaise pata?
student: kyuki hamare ghar pe aaj aaloo ki subzee bani thi.. ;->