A lady and a gentleman are wife and husband. We do not know who is older.
Someone asked them: Who is older?
The wife said: I am older.
The husband  said: I am younger.
At least one of them was lying. Who is older?

 See our previous ‘Puzzles of the Day’: 

https://tathagat.mba/puzzle-of-the-day-56/ 

https://tathagat.mba/puzzle-of-the-day-55/