It depends, I can only speak for my own understanding based on my world and country.
As far as legally an adult, you're one at the age of 20. You get a coming of age ceremony on a specific date that everyone who turned 20 can participate in. I didn't bother with mine, it means more for parents and family really, and, the world was ending and there wasn't much of a point.
As for physically, science says you're an adult at 25 because that's when your brain fully matures.
Some cultures, usually ancient ones, would consider one an adult once they reached sexual maturity.
Philosophically I feel one is an adult when they can take reasonable responsibility for their actions and support those around them.
[Which probably disqualified him from adulthood.]
Now, if this is more about if you should have fun, you should just go and have fun if that's what you want to do.
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As far as legally an adult, you're one at the age of 20. You get a coming of age ceremony on a specific date that everyone who turned 20 can participate in. I didn't bother with mine, it means more for parents and family really, and, the world was ending and there wasn't much of a point.
As for physically, science says you're an adult at 25 because that's when your brain fully matures.
Some cultures, usually ancient ones, would consider one an adult once they reached sexual maturity.
Philosophically I feel one is an adult when they can take reasonable responsibility for their actions and support those around them.
[Which probably disqualified him from adulthood.]
Now, if this is more about if you should have fun, you should just go and have fun if that's what you want to do.