Does being in your 20s mean you have to act old?

I was having this discussion with a couple of friends (Emad and Mariam) of mine last thursday. We were discussing how so many of our friends seem to have turned into grownups over night. How doing the crazy things we used to do in uni seems so juvenile at our age. Mariam and I were so dissappointed about it. I mean...why do we have to be grown ups at 20! For God's sake we are still young and having fun is not a crime. I always believed that the trick to leading a happy life is to keep the child in you alive. Keep the curious kid in you awake and looking for new things to be amazed about. From time to time be silly, sing out loud, dance the night away, have pillow fights, lie down and try to image what the clouds look like, take ur friends and go on a trip, jump into the car with your friends and go cruising with the music on really loud. We should do these things more often as we get older coz our responsibilities increase and so does our stress...so these little childish things can put a smile right back on your face :) Don't be in such a rush to grow up, what's fun about being a grown up??