In a party one of Zail Singh's friends asked him how many chappathis he could eat in an empty stomach. Zail replied "Seven". Then his friend told him "When you eat the first chappathi your stomach is no longer empty. Then how can you eat seven??"
Zail was impressed by this tricky question. So as soon as he went back home he asked his wife "How many chappathis can you eat in an empty stomach??". She replied "Five". Then Zail said: "If only you had told seven I had a nice reply for it".