When is too old to act childish? Or slightly immature?
you can always be a kid at heart and have fun, even at 20, 30.40,40,60,70 and 80/90!
but acting too immature is annoying, at 18 you are not a little kid and should not act like a child..but you can still have fun and be a kid at heart..
As long as you know your acting immature age doesnt matter. Just know when to stop.
Never. Life is too short to be serious, but as an adult (I'm in my 50's) if I say say or do something that appears to childish or immature I just shrug it off, but I know when to stop and act my age and not my shoe size. So I do have a wise old head me sometimes.