India, Sept. 17 -- Actor Akshay Kumar shared a selfie with son Aarav to celebrate his 23rd birthday on September 15. In a witty, affectionate caption he wrote, "Happy 23rd, Aarav! When I was twenty three I was learning to beat up people on screen. it's a strange feeling now to see you beat me everyday right from tech to fashion to arguments on the dinner table." In typical dad fashion, he also remarked about how grown up his son is now, adding, "Dekhte hi dekhte itna bada ho gaya hai yaar tu. you make me feel like a proud sidekick in my own story. Love you beta. Cheers to the best 23 years of my life because they've been with you." Aarav's mum, actor-author Twinkle Khanna also shared a picture of him online. Her heartfelt caption read, "Though I have an undeniable compulsion to hold on to him, it would be wise to remember that children are like the air stored in our lungs, in our custody for just a moment before the next exhalation. This may not be an entirely correct analogy because unlike breaths we can't keep popping babies in and out constantly, but you get the point right. Here's to the birthday boy. May he continue filling the world with his inate kindness." htc...