When should you grow up and stop partying/living young?

Whenever the hell you want!

When you have to...like when you get married or have a child. or if you have some other responsibility that means you cant party 24/7, cause if you do then youre just being a crap parent/husband/wife.

Partying and living young are not the same thing. Once you actually grow up, you will see the importance of living young and understand what it means. You can't do that while you are still, actually young. And you really can't if you're just immature.

Never, you only live once so live it up.

When it starts affecting you accomplishing your goals. Want to binge drink to the point of blacking out each night? Go for it! It just might make you less able to do other stuff, like have a well-paying job

Never! You take the most life has to offer and you enjoy every bit of it!

When you start having better things to do with your time. It all depends on the person, though. I don't think there's anything wrong with going out maybe a few times a month to a bar or something with friends or family, but I think by the time you're 25 going out clubbing, getting motherless drunk should be a thing of the very distant past.