Mumbai, Dec. 20 -- Among the young stars of Bollywood, if there is one actor who has managed to leave everyone smitten with her charm and cool attitude, it is Sara Ali Khan. The gorgeous diva is known to have a hilarious sense of humour and often is seen entertaining people with her funny shayari and 'Knock Knock' jokes. Recently, Varun Dhawan joined Sara for shooting Coolie No 1 and after a long day of shoot, the Simmba actress thought about goofing around with her co-star.

Sara took to Instagram to share a funny video of using her latest 'Knock Knock' joke with Varun and his reaction makes her go 'How Rude.' In the video, Varun can be seen sitting beside Sara after a day at work. Sara asks him 'Knock Knock' and Varun responds, 'Who's t...